radeonsi: preload the tess offchip ring in TES

so that it's not done multiple times in branches

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

src/gallium/drivers/radeonsi/si_shader_internal.h

@@ -191,6 +191,7 @@ struct si_shader_context {
 	/* Preloaded descriptors. */
 	LLVMValueRef esgs_ring;
 	LLVMValueRef gsvs_ring[4];
+	LLVMValueRef tess_offchip_ring;
 
 	LLVMValueRef invoc0_tess_factors[6]; /* outer[4], inner[2] */
 	LLVMValueRef gs_next_vertex[4];