freedreno: Fix warning about uninit size for the size==0 special case.

The size==0 query case would have just used uninitialized stack data for
sizing its BOs.

Fixes: 536ec9d7f5 ("freedreno: Refactor fd_resource_create_with_modifiers() into a helper")
Reviewed-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7664>

src/gallium/drivers/freedreno/freedreno_resource.c

@@ -977,6 +977,7 @@ fd_resource_allocate_and_resolve(struct pipe_screen *pscreen,
 	if (size == 0) {
 		/* note, semi-intention == instead of & */
 		debug_assert(prsc->bind == PIPE_BIND_QUERY_BUFFER);
+		*psize = 0;
 		return prsc;
 	}