zephyr: Fix serial recovery skipping on nrf53

The nRF53 mcu has moved RESETREAS register
(from POWER to RESET peripheral).
This fix uses nrfx helper to select the proper register.

Signed-off-by: Radoslaw Koppel <radoslaw.koppel@nordicsemi.no>
diff --git a/boot/zephyr/main.c b/boot/zephyr/main.c
index ab3b262..6977642 100644
--- a/boot/zephyr/main.c
+++ b/boot/zephyr/main.c
@@ -86,17 +86,13 @@
 #endif /* defined(CONFIG_LOG) && !defined(CONFIG_LOG_IMMEDIATE) */
 
 #ifdef CONFIG_SOC_FAMILY_NRF
-#include <hal/nrf_power.h>
+#include <helpers/nrfx_reset_reason.h>
 
 static inline bool boot_skip_serial_recovery()
 {
-#if NRF_POWER_HAS_RESETREAS
-    uint32_t rr = nrf_power_resetreas_get(NRF_POWER);
+    uint32_t rr = nrfx_reset_reason_get();
 
-    return !(rr == 0 || (rr & NRF_POWER_RESETREAS_RESETPIN_MASK));
-#else
-    return false;
-#endif
+    return !(rr == 0 || (rr & NRFX_RESET_REASON_RESETPIN_MASK));
 }
 #else
 static inline bool boot_skip_serial_recovery()