anv: Add support for scratch on XeHP
Rework: * Jordan: Handle per_thread_scratch==0 in anv_scratch_pool_get_surf * Jordan: Update subslices in anv_scratch_pool_alloc * Jason: Clean up the patch a bit Reviewed-by:Jason Ekstrand <jason@jlekstrand.net> Reviewed-by:
Jordan Justen <jordan.l.justen@intel.com> Part-of: <mesa/mesa!11582>