f2fs: remove unnecessary read for F2FS_FITS_IN_INODE

F2FS_FITS_IN_INODE only cares the type of f2fs inode, so there
is no need to read node page of f2fs inode.

Signed-off-by: Jia Yang <jiayang5@huawei.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>