[Mesa-dev] radv/gfx9: more vega fixes.

[Dave Airlie]

This is a good chunk of vega related fixes (with some cleanups).

I still have a few more fixes to go, but things are working a lot
better now, I've cleaned up the first round of fixes in this set.

It mostly addresses issues with the color/texture registers around
how miptrees are tiled mipmaps are layed out on gfx9.

It adds support for new rbplus blending registers which fixes
blending in the demos and games.

It also fixes some issues related to exposing linear depth texture
support.

Dave.