intel: use generated helpers for Wa_1508744258

intel: use generated helpers for Wa_1508744258

iris_disable_rhwo_optimization can only apply on gfxver 12.0, and has
a version check to that affect.  Add an assertion to warn us if the
workaround ever applies to another version.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Nanley Chery <nanley.g.chery@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21742>