Support ClearCache command

include/PSX/System/IOPorts/gpu_io.hpp

@@ -92,6 +92,10 @@ namespace JabyEngine {
                 }
             };
 
+            static constexpr struct GP0 ClearCache() {
+                return Helper::construct_cmd<struct GP0>(0x01, 0x0);
+            }
+
             static constexpr struct GP0 QuickFill(GPU::Color24 color) {
                 return Helper::construct_cmd<struct GP0>(0x02, color.raw());
             }