Replace Maxwell DMA GuestTexture usage with new swizzling API

Maxwell DMA requires swizzled copies to/from textures and earlier it had to construct an arbitrary `GuestTexture` to do so but with the introduction of the cleaner API, this has become redundant which this commit cleans up and replaces with direct calls to the API with all the necessary values.

app/src/main/cpp/skyline/gpu/texture/format.h

@@ -182,22 +182,4 @@ namespace skyline::gpu::format {
     #undef FORMAT_NORM_INT_FLOAT
 
     // @fmt:on
-
-    inline const gpu::texture::FormatBase &GetFormatForBpp(u32 bytesPerPixel) {
-        switch (bytesPerPixel) {
-            case 1:
-                return R8Uint;
-            case 2:
-                return R8G8Uint;
-            case 4:
-                return R8G8B8A8Uint;
-            case 8:
-                return R16G16B16A16Uint;
-            case 16:
-                return R32G32B32A32Uint;
-            default:
-                Logger::Error("Couldn't convert bytes per pixel: {}", bytesPerPixel);
-                return R8Uint;
-        }
-    }
 }