drm/i915/mtl: fix mocs selftest

Media GT has a different base for MOCS register, need to apply
gsi_offset to the mmio address if not using the intel_uncore_r/w
functions for register access.

Cc: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Fei Yang <fei.yang@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230421182535.292670-3-andi.shyti@linux.intel.com

drivers/gpu/drm/i915/gt/selftest_mocs.c

@@ -131,13 +131,14 @@ static int read_mocs_table(struct i915_request *rq,
 			   const struct drm_i915_mocs_table *table,
 			   u32 *offset)
 {
+	struct intel_gt *gt = rq->engine->gt;
 	u32 addr;
 
 	if (!table)
 		return 0;
 
 	if (HAS_GLOBAL_MOCS_REGISTERS(rq->engine->i915))
-		addr = global_mocs_offset();
+		addr = global_mocs_offset() + gt->uncore->gsi_offset;
 	else
 		addr = mocs_offset(rq->engine);