radeon: texture/renderbuffer overhaul.

radeon: texture/renderbuffer overhaul.

This could have been split up better, but the driver is just broken now,
so bisecting the brokenness is going to be painful no matter what.

This adds renderbuffer mapping/unmapping along with texture image allocation.
It drops all the old texture upload paths, some of which could possible be
reimplemented with the blitter later.

It also redoes the span code paths to use its own set of image mapping handlers,
along with removing the tiling decode paths for the color buffers, since
we now hope to use the blitter for this.

Signed-off-by: Dave Airlie <airlied@redhat.com>