f2fs: catch up to v4.14-rc1
This is cherry-picked from upstrea-f2fs-stable-linux-4.4.y.
Changes include:
commit
c7fd9e2b4a6876 ("f2fs: hurry up to issue discard after io interruption")
commit
603dde39653d6d ("f2fs: fix to show correct discard_granularity in sysfs")
...
commit
565f0225f95f15 ("f2fs: factor out discard command info into discard_cmd_control")
commit
c4cc29d19eaf01 ("f2fs: remove batched discard in f2fs_trim_fs")
Change-Id: Icd8a85ac0c19a8aa25cd2591a12b4e9b85bdf1c5
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>