userns: Fix posix_acl_file_xattr_userns gid conversion

The code needs to be from_kgid(make_kgid(...)...) not
from_kuid(make_kgid(...)...). Doh!
Reported-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

fs/xattr_acl.c

@@ -45,7 +45,7 @@ static void posix_acl_fix_xattr_userns(
 			break;
 		case ACL_GROUP:
 			gid = make_kgid(from, le32_to_cpu(entry->e_id));
-			entry->e_id = cpu_to_le32(from_kuid(to, uid));
+			entry->e_id = cpu_to_le32(from_kgid(to, gid));
 			break;
 		default:
 			break;