D3D: Fix Virtual XFB viewport.

[CrossVR]

Looks like I was incorrect about swapping the bottom and top members.

This PR also fixes a problem where the framebuffer was not invalidated when XFB modes are switched.

[degasus]

Yeah, stupid OGL... LGTM

[CrossVR]

@degasus Btw, what do you think of merging Television.cpp into FramebufferManager.cpp? The only thing we do in Television.cpp is decode YUV data which is normally done through XFBSource::DecodeToTexture which is left unimplemented in D3D.

Actually we should probably merge Television.cpp into XFBEncoder.cpp, since Television.cpp is nothing more than the decoder counterpart. We could rename this new module to TextureConverter, which would reflect the OGL architecture. We would then call the decode function from XFBSource::DecodeToTexture just like OGL.

Also, I'm going to add one more small commit to fix viewport problems when switching between Virtual and Real XFB.

[CrossVR]

This PR is ready for review. I hope you don't mind that I included a couple of code style fixes that were annoying me.

[Sonicadvance1]

LGTM