Merge commit '73450231' into android-4.4

Synced to the latest commit for merge:
73450231 f2fs: run fstrim asynchronously if runtime discard is on

Change-Id: Icec09d14f2768dfaa1a0691eac275f68adbf470b
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>

Conflicts:
    fs/crypto/fscrypt_private.h
    fs/crypto/keyinfo.c
    fs/f2fs/data.c
    fs/f2fs/f2fs.h
    fs/f2fs/namei.c
    fs/f2fs/segment.c
    fs/f2fs/super.c
    include/uapi/linux/fs.h
        Resolved conflicts based on android-4.4:fs/f2fs codebase.

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>