dragon: Update prebuilt kernel to 31730abfac9b25e448b566df31630826de6228fd
Build: trybot-smaug-paladin/R50-7897.1.0-b1086
Changes include:
* 31730ab UPSTREAM: ALSA: timer: Fix race among timer ioctls
* d0926fd UPSTREAM: usbnet: cleanup after bind() in probe()
* 0822254 UPSTREAM: ALSA: timer: Fix leak in events via snd_timer_user_tinterrupt
* 0ea6620 UPSTREAM: net: fix infoleak in rtnetlink
* d3a0372 UPSTREAM: net: validate the range we feed to iov_iter_init() in sys_sendto/sys_recvfrom
* 0921de3 UPSTREAM: ipv6: add complete rcu protection around np->opt
* c059f53 UPSTREAM: USB: usbfs: fix potential infoleak in devio
* 07d3fe1 CHROMIUM: drm/nouveau: add more messages for nouveau PM
* fa4a710 CHROMIUM: tegra/drm: ad5823: Add set position retry
* d29b5b5 UPSTREAM: ALSA: timer: Fix leak in SNDRV_TIMER_IOCTL_PARAMS
* 7c3680e HACK: memory: tegra: Do not go to 40.8 MHz EMC
* 8de6dc4 CHROMIUM: drm/nouveau: Zeroing GM20b MMU debug buffer
* c0a80ce CHROMIUM: spidev: fix heap overflow vulnerability
* 6e9f83a CHROMIUM: arm64: dragon: disable CONFIG_ION_TEST
* de5666f CHROMIUM: drm/nouveau: Use vmalloc instead of kmalloc
* a59d327 CHROMIUM: arm64: dragon: enable CONFIG_SECURITY_PERF_EVENTS_RESTRICT
* 6878961 ANDROID: FROMLIST: security,perf: Allow further restriction of perf_event_open
* d2d7613 ANDROID: BACKPORT: perf tools: Document the perf sysctls
* 6e8609f CHROMIUM: drm/nouveau/gr/gk20a: add FECS halt method
* 6e6f1c9 CHROMIUM: drm/nouveau/fifo: add recovery for MMU fault
* d15b6e9 CHROMIUM: drm/nouveau/gr: regenerate grctx for recovery
* 23042e0 CHROMIUM: drm/nouveau/pmu/gm20b: increase PMU timeout to boot FECS
* efc2428 ANDROID: Don't show empty tag stats for unprivileged uids
* 98b9cbf UPSTREAM: ALSA: seq: Fix race at timer setup and close
* d77a931 CHROMIUM: net: wireless: bcmdhd: security enhancement for BRCM ether type
Bug: 28694392
Bug: 28744625
Bug: 28980217
Bug: 28620102
Bug: 28759139
Bug: 28746669
Bug: 28619695
Bug: 29321797
Bug: 28693336
Bug: 28980557
Bug: 28762106
Bug: 28430009
Bug: 28939740
Bug: 29093588
Bug: 29119870
Bug: 28695438
Bug: 26492805
Change-Id: I89ec60d1902346e3ad3608218b4a634b6b0e9db3
