drm/xe: fix multicast support for Xe_LP platforms

Xe_LP has six sublices per slice.

v2: fixed commit message and subject (Matt)

Bspec: 66696
Fixes: bde5d767 ("drm/xe: Add helper macro to loop each DSS")
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240405-mcr_adlp-v2-1-2fd1e4325ef2@intel.comSigned-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

drivers/gpu/drm/xe/xe_gt_mcr.c

@@ -297,7 +297,12 @@ static void init_steering_mslice(struct xe_gt *gt)
 
 static unsigned int dss_per_group(struct xe_gt *gt)
 {
-	return gt_to_xe(gt)->info.platform == XE_PVC ? 8 : 4;
+	if (gt_to_xe(gt)->info.platform == XE_PVC)
+		return 8;
+	else if (GRAPHICS_VERx100(gt_to_xe(gt)) >= 1250)
+		return 4;
+	else
+		return 6;
 }
 
 /**