XXXX introduce drv_sectohz

@@ -287,11 +287,11 @@
                          * which we want to avoid. Also, the client is prepared
                          * to wait any way.
                          */
                         CALLB_CPR_SAFE_BEGIN(&cprinfo);
                         mutex_exit(&cbuf_list_lock);
-                        delay(30 * drv_usectohz(1000000));
+                        delay(drv_sectohz(30));
                         mutex_enter(&cbuf_list_lock);
                         CALLB_CPR_SAFE_END(&cprinfo, &cbuf_list_lock);
                 }
 
                 /* Wait for new work to arrive */