Revert "drm/radeon: Use write-combined CPU mappings of ring buffers with PCIe"
Revert "drm/radeon: Use write-combined CPU mappings of ring buffers with PCIe"

This reverts commit 1490434f0da63afc6006411c8829c6a7935a4e7e.

Several people have reported regressions with this patch on kabini.

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs