ext4: correct max_inline_xattr_value_size computing

hulk inclusion
category: bugfix
bugzilla: 186866, https://gitee.com/openeuler/kernel/issues/I5DTBL


CVE: NA

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If the ext4 inode does not have xattr space, 0 is returned in the
get_max_inline_xattr_value_size function. Otherwise, the function returns
a negative value when the inode does not contain EXT4_STATE_XATTR.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>