decoder/image: Fix incorrect G24R8 component sizes in GetComponentSize()

The components' sizes were mismatched. This corrects that.

src/video_core/shader/decode/image.cpp

@@ -201,10 +201,10 @@ u32 GetComponentSize(TextureFormat format, std::size_t component) {
         return 0;
     case TextureFormat::G24R8:
         if (component == 0) {
-            return 8;
+            return 24;
         }
         if (component == 1) {
-            return 24;
+            return 8;
         }
         return 0;
     case TextureFormat::G8R8: