Xenial update to 4.4.81 stable release

SRU Justification

    Impact:
       The upstream process for stable tree updates is quite similar
       in scope to the Ubuntu SRU process, e.g., each patch has to
       demonstrably fix a bug, and each patch is vetted by upstream
       by originating either directly from a mainline/stable Linux tree or
       a minimally backported form of that patch. The 4.4.81 upstream stable
       patch set is now available. It should be included in the Ubuntu
       kernel as well.

       git://git.kernel.org/

    TEST CASE: TBD

The following patches from the 4.4.81 stable release shall be applied:
* libata: array underflow in ata_find_dev()
* workqueue: restore WQ_UNBOUND/max_active==1 to be ordered
* ALSA: hda - Fix speaker output from VAIO VPCL14M1R
* ASoC: do not close shared backend dailink
* KVM: async_pf: make rcu irq exit if not triggered from idle task
* mm/page_alloc: Remove kernel address exposure in free_reserved_area()
* ext4: fix SEEK_HOLE/SEEK_DATA for blocksize < pagesize
* ext4: fix overflow caused by missing cast in ext4_resize_fs()
* ARM: dts: armada-38x: Fix irq type for pca955
* media: platform: davinci: return -EINVAL for VPFE_CMD_S_CCDC_RAW_PARAMS
  ioctl
* target: Avoid mappedlun symlink creation during lun shutdown
* iscsi-target: Always wait for kthread_should_stop() before kthread exit
* iscsi-target: Fix early sk_data_ready LOGIN_FLAGS_READY race
* iscsi-target: Fix initial login PDU asynchronous socket close OOPs
* iscsi-target: Fix delayed logout processing greater than
  SECONDS_FOR_LOGOUT_COMP
* iser-target: Avoid isert_conn->cm_id dereference in isert_login_recv_done
* mm, mprotect: flush TLB if potentially racing with a parallel reclaim
  leaving stale TLB entries
* media: lirc: LIRC_GET_REC_RESOLUTION should return microseconds
* f2fs: sanity check checkpoint segno and blkoff
* drm: rcar-du: fix backport bug
* saa7164: fix double fetch PCIe access condition
* ipv4: ipv6: initialize treq->txhash in cookie_v[46]_check()
* net: Zero terminate ifr_name in dev_ifname().
* ipv6: avoid overflow of offset in ip6_find_1stfragopt
* ipv4: initialize fib_trie prior to register_netdev_notifier call.
* rtnetlink: allocate more memory for dev_set_mac_address()
* mcs7780: Fix initialization when CONFIG_VMAP_STACK is enabled
* openvswitch: fix potential out of bound access in parse_ct
* packet: fix use-after-free in prb_retire_rx_blk_timer_expired()
* ipv6: Don't increase IPSTATS_MIB_FRAGFAILS twice in ip6_fragment()
* net: ethernet: nb8800: Handle all 4 RGMII modes identically
* dccp: fix a memleak that dccp_ipv6 doesn't put reqsk properly
* dccp: fix a memleak that dccp_ipv4 doesn't put reqsk properly
* dccp: fix a memleak for dccp_feat_init err process
* sctp: don't dereference ptr before leaving _sctp_walk_{params, errors}()
* sctp: fix the check for _sctp_walk_params and _sctp_walk_errors
* net/mlx5: Fix command bad flow on command entry allocation failure
* net: phy: Correctly process PHY_HALTED in phy_stop_machine()
* net: phy: Fix PHY unbind crash
* xen-netback: correctly schedule rate-limited queues
* sparc64: Measure receiver forward progress to avoid send mondo timeout
* wext: handle NULL extra data in iwe_stream_add_point better
* sh_eth: R8A7740 supports packet shecksumming
* net: phy: dp83867: fix irq generation
* tg3: Fix race condition in tg3_get_stats64().
* x86/boot: Add missing declaration of string functions
* phy state machine: failsafe leave invalid RUNNING state
* scsi: qla2xxx: Get mutex lock before checking optrom_state
* drm/virtio: fix framebuffer sparse warning
* virtio_blk: fix panic in initialization error path
* ARM: 8632/1: ftrace: fix syscall name matching
* mm, slab: make sure that KMALLOC_MAX_SIZE will fit into MAX_ORDER
* lib/Kconfig.debug: fix frv build failure
* signal: protect SIGNAL_UNKILLABLE from unintentional clearing.
* mm: don't dereference struct page fields of invalid pages
* workqueue: implicit ordered attribute should be overridable
* Linux 4.4.81