v3dv: Fix assert using assign instead of compare.

Fix defect reported by Coverity Scan.

Assign instead of compare (PW.ASSIGN_WHERE_COMPARE_MEANT)
assign_where_compare_meant: use of "=" where "==" may have been intended

Fixes: c75846e674 ("v3dv: implement DRM modifier setup for WSI")
Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7124>

src/broadcom/vulkan/v3dv_image.c

@@ -385,7 +385,7 @@ v3dv_GetImageDrmFormatModifierPropertiesEXT(
 {
    V3DV_FROM_HANDLE(v3dv_image, image, _image);
 
-   assert(pProperties->sType =
+   assert(pProperties->sType ==
           VK_STRUCTURE_TYPE_IMAGE_DRM_FORMAT_MODIFIER_PROPERTIES_EXT);
 
    pProperties->drmFormatModifier = image->drm_format_mod;