asahi: Wire up all BCn formats
We have these native. Passes the relevant piglits. Large reduction in memory usage on Xonotic on higher settings (8x less memory per texture), which allows Xonotic to run at high settings without OOMing.
Signed-off-by: Alyssa Rosenzweig alyssa@rosenzweig.io Tested-by: Asahi Lina lina@asahilina.net