drm/xe: fix xe_mmio_total_vram_size

As also cause issue on PVC, moving back
to what we did before stolen was
introduced
Signed-off-by: Philippe Lecluse <philippe.lecluse@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_mmio.c

@@ -159,12 +159,8 @@ int xe_mmio_total_vram_size(struct xe_device *xe, u64 *vram_size, u64 *usable_si
 
 	if (!xe->info.has_flat_ccs)  {
 		*vram_size = pci_resource_len(pdev, GEN12_LMEM_BAR);
-		if (usable_size) {
-			if (xe->info.platform == XE_DG1)
-				*usable_size = xe_mmio_read64(gt, GEN12_GSMBASE.reg);
-			else
-				*usable_size = *vram_size;
-		}
+		if (usable_size)
+			*usable_size = min(*vram_size, xe_mmio_read64(gt, GEN12_GSMBASE.reg));
 		return 0;
 	}