i965: Don't override subslice count to 4 on Gen11.

Gen9-10 have fewer than 4 subslices per slice, so they need this to be
rounded up.  Gen11 isn't documented as needing this hack, and it can
also have more than 4 subslices, so the hack actually can break things.

Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>

src/mesa/drivers/dri/i965/brw_program.c

@@ -407,7 +407,7 @@ brw_alloc_stage_scratch(struct brw_context *brw,
        * and we wish to view that there are 4 subslices per slice
        * instead of the actual number of subslices per slice.
        */
-      if (devinfo->gen >= 9)
+      if (devinfo->gen >= 9 && devinfo->gen < 11)
          subslices = 4 * brw->screen->devinfo.num_slices;
 
       unsigned scratch_ids_per_subslice;