f2fs_io: support get_advise command

Support get_advise command to get i_advise field value and info
in file.

For example:
f2fs_io get_advise /mnt/f2fs/foo.so
i_advise=0x11, advise_type: cold keep_size

Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
3 files changed