r600g: prevent hardware blitting based on resource usage

It doesn't make much sense for STAGING and STREAM resources to be
hardware blitted into VRAM.

src/gallium/drivers/r600/r600_texture.c

@@ -313,7 +313,14 @@ static boolean permit_hardware_blit(struct pipe_screen *screen,
                                 PIPE_BIND_SAMPLER_VIEW))
 		return FALSE;
 
-	return TRUE;
+	switch (res->usage) {
+	case PIPE_USAGE_STREAM:
+	case PIPE_USAGE_STAGING:
+		return FALSE;
+
+	default:
+		return TRUE;
+	}
 }
 
 static boolean r600_texture_get_handle(struct pipe_screen* screen,