iris: Check that mem_fence_bo was created

Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Fixes: 8e8097245f ("iris: Emit STATE_SYSTEM_MEM_FENCE_ADDRESS")
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32716>

src/gallium/drivers/iris/iris_bufmgr.c

@@ -2478,8 +2478,8 @@ iris_bufmgr_create(struct intel_device_info *devinfo, int fd, bool bo_reuse)
    if (devinfo->verx10 >= 200) {
       bufmgr->mem_fence_bo = iris_bo_alloc(bufmgr, "mem_fence", 4096, 4096,
                                            IRIS_MEMZONE_OTHER, BO_ALLOC_SMEM);
-         if (!bufmgr->dummy_aux_bo)
-            goto error_alloc_bo;
+      if (!bufmgr->mem_fence_bo)
+         goto error_alloc_bo;
    }
 
    return bufmgr;