ext2: Remove redundant check on s_inode_size

The case of (EXT2_INODE_SIZE(sb) == 0) is included in
(sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE).
So there is no need to check again.

Signed-off-by: Liu Xiang <liu.xiang6@zte.com.cn>
Signed-off-by: Jan Kara <jack@suse.cz>