f2fs: convert to use sbi directly

[ Upstream commit c3355ea9 ]

F2FS_I_SB(inode) is redundant.

Signed-off-by: Yangtao Li <frank.li@vivo.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Stable-dep-of: b7d797d2 ("f2fs: compress: relocate some judgments in f2fs_reserve_compress_blocks")
Signed-off-by: Sasha Levin <sashal@kernel.org>