ext4: correct comment of ext4_xattr_cmp

The ext4_xattr_cmp never returns negative error number. Correct possible
return value in ext4_xattr_cmp's comment.
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Link: https://patch.msgid.link/20240606125508.1459893-2-shikemeng@huaweicloud.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/xattr.c

@@ -3065,8 +3065,7 @@ ext4_xattr_block_cache_insert(struct mb_cache *ea_block_cache,
  *
  * Compare two extended attribute blocks for equality.
  *
- * Returns 0 if the blocks are equal, 1 if they differ, and
- * a negative error number on errors.
+ * Returns 0 if the blocks are equal, 1 if they differ.
  */
 static int
 ext4_xattr_cmp(struct ext4_xattr_header *header1,