Implement RGB565 Framebuffer format

src/video_core/gpu.cpp

@@ -18,6 +18,8 @@ u32 FramebufferConfig::BytesPerPixel(PixelFormat format) {
     case PixelFormat::ABGR8:
     case PixelFormat::BGRA8:
         return 4;
+    case PixelFormat::RGB565:
+        return 2;
     default:
         return 4;
     }