radv: fix CP DMA with NULL PRT pages on GFX8-9

On GFX8-9 (starting from Polaris10), CP DMA is broken with NULL PRT
pages. It doesn't read 0 and doesn't discard writes which can cause
GPU hangs.

Fix that by always using the compute path when a BO is sparse.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/12828
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35071>
8 files changed