test: Add a generic function to skip delays

At present this feature is sandbox-specific. For running tests on boards,
we need a nop version. Add one.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/test/test.h

@@ -170,6 +170,22 @@ static inline int test_load_other_fdt(struct unit_test_state *uts)
 	return ret;
 }
 
+/**
+ * Control skipping of time delays
+ *
+ * Some tests have unnecessay time delays (e.g. USB). Allow these to be
+ * skipped to speed up testing
+ *
+ * @param skip_delays	true to skip delays from now on, false to honour delay
+ *			requests
+ */
+static inline void test_set_skip_delays(bool skip_delays)
+{
+#ifdef CONFIG_SANDBOX
+	state_set_skip_delays(skip_delays);
+#endif
+}
+
 /**
  * test_set_eth_enable() - Enable / disable Ethernet
  *