panfrost: Texture refactor

Let's make the texture upload code not insane.

Was it worth it? Who knows :(

WIP because it'll probably break AFBC at the moment. AFBC still works for glmark (by "accident"). I added a comment that this will need to be addressed when we revisit AFBC, but seeing as it's already nonconformant I didn't want to spend too much time on this at the moment.