drm/i915/xelpmp: Consider GSI offset when doing MCR lookups

MCR range tables use the final MMIO offset of a register (including the
0x380000 GSI offset when applicable).  Since the i915_mcr_reg_t passed
as a parameter during steering lookup does not include the GSI offset,
we need to add it back in for GSI registers before searching the tables.

Fixes: a7ec65fc ("drm/i915/xelpmp: Add multicast steering for media GT")
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230214001906.1477370-1-matthew.d.roper@intel.com
(cherry picked from commit d6683bbe)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

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

@@ -559,12 +559,15 @@ static bool reg_needs_read_steering(struct intel_gt *gt,
 				    i915_mcr_reg_t reg,
 				    enum intel_steering_type type)
 {
-	const u32 offset = i915_mmio_reg_offset(reg);
+	u32 offset = i915_mmio_reg_offset(reg);
 	const struct intel_mmio_range *entry;
 
 	if (likely(!gt->steering_table[type]))
 		return false;
 
+	if (IS_GSI_REG(offset))
+		offset += gt->uncore->gsi_offset;
+
 	for (entry = gt->steering_table[type]; entry->end; entry++) {
 		if (offset >= entry->start && offset <= entry->end)
 			return true;