drm/xe: Avoid reading RMW registers in emit_wa_job

To allow VFs properly handle LRC WAs, we should postpone doing
all RMW register operations and let them be run by the engine
itself, since attempt to perform read registers from within the
driver will fail on the VF. Use MI_MATH and ALU for that.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250303173522.1822-4-michal.wajdeczko@intel.com