drm/i915/guc: Simplify/extend platform check for Wa_14018913170

The above w/a is required for every platform that the i915 driver
supports. It is fixed on the latest platforms but they are only
supported by Xe instead of i915. So just remove the platform check
completely and keep the code simple.

v2: Add extra comment (review feedback from Rodrigo).

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240223202846.1532176-1-John.C.Harrison@Intel.com