r600g: don't set dirty_db_mask for a flushed depth texture

A flush depth texture is never set as a depth buffer and never flushed.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

src/gallium/drivers/r600/r600_texture.c

@@ -753,8 +753,6 @@ void r600_init_flushed_depth_texture(struct pipe_context *ctx,
 
 	if (staging)
 		resource.flags |= R600_RESOURCE_FLAG_TRANSFER;
-	else
-		rtex->dirty_db_mask = (1 << (resource.last_level+1)) - 1;
 
 	*flushed_depth_texture = (struct r600_resource_texture *)ctx->screen->resource_create(ctx->screen, &resource);
 	if (*flushed_depth_texture == NULL) {