refactor(core): update power API to Zephyr v2.5.0

See: https://github.com/zephyrproject-rtos/zephyr/pull/29410
PR: https://github.com/zmkfirmware/zmk/pull/736

app/Kconfig

@@ -263,11 +263,8 @@ config ZMK_SLEEP
 
 if ZMK_SLEEP
 
-config SYS_POWER_DEEP_SLEEP_STATES
-	default y
-
 choice SYS_PM_POLICY
-	default SYS_PM_POLICY_APP
+	default PM_POLICY_APP
 endchoice
 
 config DEVICE_POWER_MANAGEMENT

app/src/power.c

@@ -23,18 +23,12 @@ bool is_usb_power_present() {
 #endif /* CONFIG_USB */
 }
 
-enum power_states sys_pm_policy_next_state(int32_t ticks) {
-#ifdef CONFIG_SYS_POWER_DEEP_SLEEP_STATES
-#ifdef CONFIG_HAS_SYS_POWER_STATE_DEEP_SLEEP_1
+struct pm_state_info pm_policy_next_state(int32_t ticks) {
     if (zmk_activity_get_state() == ZMK_ACTIVITY_SLEEP && !is_usb_power_present()) {
-        return SYS_POWER_STATE_DEEP_SLEEP_1;
+        return (struct pm_state_info){PM_STATE_SOFT_OFF, 0, 0};
     }
-#endif /* CONFIG_HAS_SYS_POWER_STATE_DEEP_SLEEP_1 */
-#endif /* CONFIG_SYS_POWER_DEEP_SLEEP_STATES */
 
-    return SYS_POWER_STATE_ACTIVE;
+    return (struct pm_state_info){PM_STATE_ACTIVE, 0, 0};
 }
 
-bool sys_pm_policy_low_power_devices(enum power_states pm_state) {
-    return sys_pm_is_sleep_state(pm_state);
-}
+__weak bool pm_policy_low_power_devices(enum pm_state state) { return pm_is_sleep_state(state); }