[nrf fromtree] drivers: serial: nrfx_uarte: Fix pin retention

b6d4542 Added support for pin retention but it was added
only to the case when device PM is used. There is another mode
in which UARTE is disabled when idle (low power mode) and in
that case pin retention must also be added.

Signed-off-by: Krzysztof Chruściński <[email protected]>
(cherry picked from commit 760bba6)

Author: nordic-krch

drivers/serial/uart_nrfx_uarte.c

@@ -590,6 +590,9 @@ static void uarte_periph_enable(const struct device *dev)
 
 	(void)data;
 	nrf_uarte_enable(uarte);
+#ifdef CONFIG_SOC_NRF54H20_GPD
+	nrf_gpd_retain_pins_set(config->pcfg, false);
+#endif
 #if UARTE_BAUDRATE_RETENTION_WORKAROUND
 	nrf_uarte_baudrate_set(uarte,
 		COND_CODE_1(CONFIG_UART_USE_RUNTIME_CONFIGURE,
@@ -702,6 +705,11 @@ static void uarte_disable_locked(const struct device *dev, uint32_t dis_mask)
 	}
 #endif
 
+#ifdef CONFIG_SOC_NRF54H20_GPD
+	const struct uarte_nrfx_config *cfg = dev->config;
+
+	nrf_gpd_retain_pins_set(cfg->pcfg, true);
+#endif
 	nrf_uarte_disable(get_uarte_instance(dev));
 }
 
@@ -2103,9 +2111,6 @@ static void uarte_pm_resume(const struct device *dev)
 
 	if (IS_ENABLED(CONFIG_PM_DEVICE_RUNTIME) || !LOW_POWER_ENABLED(cfg)) {
 		uarte_periph_enable(dev);
-#ifdef CONFIG_SOC_NRF54H20_GPD
-		nrf_gpd_retain_pins_set(cfg->pcfg, false);
-#endif
 	}
 }