drm/xe: fix WA 14018094691

This WA is applied while initializing the media GT, but it a primary
GT WA (because it modifies a register on the primary GT), so the XE_WA
macro is returning false even when the WA should be applied.
Fix this by using the primary GT in the macro.

Note that this WA only applies to PXP and we don't yet support that in
Xe, so there are no negative effects to this bug, which is why we didn't
see any errors in testing.

v2: use the primary GT in the macro instead of marking the WA as
platform-wide (Lucas, Matt).

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240807235333.1370915-1-daniele.ceraolospurio@intel.com