panfrost: Avoid overlapping copy

CID 1457486:  Memory - corruptions  (OVERLAPPING_COPY)

Assigning "(*attr).extra_flags = (*attr).size = 0U" to "(*attr).stride",
which have overlapping memory +locations.

Coverity.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3684>

src/panfrost/encoder/pan_attributes.c

@@ -202,7 +202,9 @@ panfrost_instance_id(
         union mali_attr *attr)
 {
         attr->elements = MALI_ATTR_INSTANCEID;
-        attr->stride = attr->extra_flags = attr->size = 0;
+        attr->stride = 0;
+        attr->extra_flags = 0;
+        attr->size = 0;
         
         /* POT records have just a shift directly with an off-by-one for
          * unclear reasons. NPOT records have a magic divisor smushed into the