asahi: Remove obnoxious workaround

Now that we're not hardcoded any magic BO IDs, there is no minimum
number of allocations needed. Remove the unneeded -- and obnoxious --
workaround of allocating unused BOs on startup.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13784>
1 file changed