radeonsi: re-create the aux context in si_create_context

radeonsi: re-create the aux context in si_create_context

If a GPU reset occurs, all contexts need to be recreated.
So instead of re-creating the aux context during the flush
of a normal context, we build a new one if we detect that
it needs to be updated.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10179>