Metal: Fix SPIR-V → MSL compilation on iOS targets

Author: stuartcarnie

drivers/metal/rendering_device_driver_metal.mm

@@ -2045,6 +2045,7 @@ void deserialize(BufReader &p_reader) {
 
 #if TARGET_OS_IPHONE
 	msl_options.ios_use_simdgroup_functions = (*device_properties).features.simdPermute;
+	msl_options.ios_support_base_vertex_instance = true;
 #endif
 
 	bool disable_argument_buffers = false;