staging: fsl-mc: return -EINVAL for all fsl_mc_portal_allocate() failures

There are some error paths that allow for a NULL new_mc_io and err = 0
return code. Return -EINVAL instead.
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Stuart Yoder <stuart.yoder@nxp.com>
Acked-by: German Rivera <german.rivera@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fsl-mc/bus/mc-allocator.c

@@ -293,6 +293,7 @@ int __must_check fsl_mc_portal_allocate(struct fsl_mc_device *mc_dev,
 	if (error < 0)
 		return error;
 
+	error = -EINVAL;
 	dpmcp_dev = resource->data;
 	if (WARN_ON(!dpmcp_dev))
 		goto error_cleanup_resource;