xfs: don't allow negative error tags

Errors go from zero which means no error to XFS_ERRTAG_MAX (22).  My
static checker complains that xfs_errortag_add() puts an upper bound on
this but not a lower bound.  Let's fix it by making it unsigned.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>


diff --git a/fs/xfs/xfs_error.c b/fs/xfs/xfs_error.c
index 88693a9..acd9413 100644
--- a/fs/xfs/xfs_error.c
+++ b/fs/xfs/xfs_error.c
@@ -55,7 +55,7 @@
 }
 
 int
-xfs_errortag_add(int error_tag, xfs_mount_t *mp)
+xfs_errortag_add(unsigned int error_tag, xfs_mount_t *mp)
 {
 	int i;
 	int len;