drm/xe: Correct lineage for Wa_22014953428 and only check with valid GT

drm/xe: Correct lineage for Wa_22014953428 and only check with valid GT

Wa_22014953428 was incorrectly labelled with a release-specific ID
number rather than the cross-platform lineage number; fix that.
Also check that the GT is not NULL before trying to lookup the
workaround in it.  Since this workaround only applies to DG2 discrete
GPUs (where the primary GT cannot be disabled), no coverage is lost.

Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>
Link: https://lore.kernel.org/r/20251013200944.2499947-43-matthew.d.roper@intel.com
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>