zink: do not read outside of array

We need to bounds-check *before* we index the array, otherwise we peek
beyond the end of it.

Caught by Valgrind.

Fixes: dd29a7e5b0 ("zink: move descriptor barrier handling to main update function")
Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10367>

src/gallium/drivers/zink/zink_descriptors.c

@@ -1224,7 +1224,7 @@ zink_descriptors_update(struct zink_context *ctx, struct zink_screen *screen, bo
                                                is_compute, cache_hit[ZINK_DESCRIPTOR_TYPE_IMAGE],
                                                need_resource_refs[ZINK_DESCRIPTOR_TYPE_IMAGE]);
 
-   for (int h = 0; zds[h] && h < ZINK_DESCRIPTOR_TYPES; h++) {
+   for (int h = 0; h < ZINK_DESCRIPTOR_TYPES && zds[h]; h++) {
       /* skip null descriptor sets since they have no resources */
       if (!zds[h]->hash)
          continue;