tests: tickless_concept: Fix failures seen on NXP RT595

Add the os_timer as a wakeup source so we can exit
deep-sleep modes.

Signed-off-by: Mahesh Mahadevan <mahesh.mahadevan@nxp.com>

Author: mmahadevan108

tests/kernel/tickless/tickless_concept/boards/mimxrt595_evk_cm33.conf

@@ -0,0 +1,10 @@
+#
+# Copyright 2022, NXP
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+# Turn on Device Level Power Management as we wish
+# to reconfigure the FlexSPI pins for power savings
+# when transitioning the SoC to Deep Low Power modes.
+CONFIG_PM_DEVICE=y

tests/kernel/tickless/tickless_concept/boards/mimxrt595_evk_cm33.overlay

@@ -0,0 +1,10 @@
+/*
+ * Copyright 2022, NXP
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&os_timer {
+	status = "okay";
+	wakeup-source;
+};