soc: nxp: rt5xx: Improve poweroff for rt5xx

This commit introduced the following changes:
1. MIMXRT595 poweroff corresponds to its full
deep power down mode not deep power down mode.
2. Enable OSC32K before poweroff, the OSC32K
is the clock source of the wakeup source RTC.
3. Enable RTC wake-up function.

Signed-off-by: Zhaoxiang Jin <[email protected]>

Author: ZhaoxiangJin

soc/nxp/imxrt/imxrt5xx/cm33/poweroff.c

@@ -4,20 +4,21 @@
  */
 
 #include <zephyr/sys/poweroff.h>
-#include <zephyr/toolchain.h>
-
 #include <fsl_power.h>
 
 static const uint32_t exclude_from_pd[] = {0, 0, 0, 0};
 
 void z_sys_poweroff(void)
 {
+	CLOCK_EnableOsc32K(true);
+	SYSCTL0->STARTEN1 |= SYSCTL0_STARTEN1_RTC_LITE0_WAKEUP_MASK;
+
 	/* Disable ISP Pin pull-ups and input buffers to avoid current leakage */
 	IOPCTL->PIO[1][15] = 0;
 	IOPCTL->PIO[3][28] = 0;
 	IOPCTL->PIO[3][29] = 0;
 
-	POWER_EnterDeepPowerDown(exclude_from_pd);
+	POWER_EnterFullDeepPowerDown(exclude_from_pd);
 
 	CODE_UNREACHABLE;
 }