v3d: If the modifier is not known on BO import, default to linear for RO.

Part of fixing DRI3 rendering with RO on X11.

Fixes: e113b21cb7 ("v3d: Add renderonly support.")

src/gallium/drivers/v3d/v3d_resource.c

@@ -814,9 +814,11 @@ v3d_resource_from_handle(struct pipe_screen *pscreen,
                 rsc->tiled = false;
                 break;
         case DRM_FORMAT_MOD_BROADCOM_UIF:
-        case DRM_FORMAT_MOD_INVALID:
                 rsc->tiled = true;
                 break;
+        case DRM_FORMAT_MOD_INVALID:
+                rsc->tiled = screen->ro == NULL;
+                break;
         default:
                 fprintf(stderr,
                         "Attempt to import unsupported modifier 0x%llx\n",