boards: nxp: frdm_mcxn236: Enabled IRTC Driver.

Enabling the IRTC Driver for the frdm_mcxn236 board.
Tested with example samples/drivers/rtc.

Signed-off-by: Neil Chen <[email protected]>

Author: NeilChen93

boards/nxp/frdm_mcxn236/doc/index.rst

@@ -80,6 +80,8 @@ The FRDM-MCXN236 board configuration supports the following hardware features:
 +-----------+------------+-------------------------------------+
 | MRT       | on-chip    | counter                             |
 +-----------+------------+-------------------------------------+
+| RTC       | on-chip    | rtc                                 |
++-----------+------------+-------------------------------------+
 
 Targets available
 ==================

boards/nxp/frdm_mcxn236/frdm_mcxn236.dts

@@ -27,6 +27,7 @@
 	aliases{
 		watchdog0 = &wwdt0;
 		pwm-0 = &flexpwm1_pwm0;
+		rtc = &rtc;
 	};
 };
 
@@ -146,3 +147,7 @@ zephyr_udc0: &usb1 {
 &mrt0_channel0 {
 	status = "okay";
 };
+
+&rtc {
+	status = "okay";
+};