drm/xe: Constify xe_dss_mask_group_ffs()

Due to how xe_dss_mask_t is implemented, the type is a pointer. Since
this is only used for looking up the bits, make it const so it can be
used together with a const gt passed around.
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_gt_topology.c

@@ -123,7 +123,7 @@ xe_gt_topology_dump(struct xe_gt *gt, struct drm_printer *p)
  * groupsize and groupnum are non-zero.
  */
 unsigned int
-xe_dss_mask_group_ffs(xe_dss_mask_t mask, int groupsize, int groupnum)
+xe_dss_mask_group_ffs(const xe_dss_mask_t mask, int groupsize, int groupnum)
 {
 	return find_next_bit(mask, XE_MAX_DSS_FUSE_BITS, groupnum * groupsize);
 }

drivers/gpu/drm/xe/xe_gt_topology.h

@@ -15,7 +15,7 @@ void xe_gt_topology_init(struct xe_gt *gt);
 void xe_gt_topology_dump(struct xe_gt *gt, struct drm_printer *p);
 
 unsigned int
-xe_dss_mask_group_ffs(xe_dss_mask_t mask, int groupsize, int groupnum);
+xe_dss_mask_group_ffs(const xe_dss_mask_t mask, int groupsize, int groupnum);
 
 bool
 xe_gt_topology_has_dss_in_quadrant(struct xe_gt *gt, int quad);