dts: stm32wl: Configure LPUART wakeup line

Rather than configuring in serial_wakeup sample, define LPUART1 wakeup
line in wl.dtsi file.

Additionally make few cosmetic changes to nucleo_wl55rj overlay in
serial wakeup sample.

Signed-off-by: Erwan Gouriou <[email protected]>

Author: erwango

dts/arm/st/wl/stm32wl.dtsi

@@ -259,6 +259,7 @@
 			clocks = <&rcc STM32_CLOCK_BUS_APB1_2 0x00000001>;
 			resets = <&rctl STM32_RESET(APB1H, 0U)>;
 			interrupts = <38 0>;
+			wakeup-line = <28>;
 			status = "disabled";
 		};
 

samples/boards/stm32/power_mgmt/serial_wakeup/boards/nucleo_wl55jc.overlay

@@ -4,17 +4,20 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-&clk_lse {
-	status = "okay";
-};
 
-/* LPUART1 clock source on LSE : set console at 9600 */
 &lpuart1 {
-	/delete-property/ clocks;
+	/* Set domain clock to LSE to allow wakeup from Stop mode */
 	clocks = <&rcc STM32_CLOCK_BUS_APB1_2 0x00000001>,
 		<&rcc STM32_SRC_LSE LPUART1_SEL(3)>;
 
+	/* LPUART1 clock source on LSE : set console at 9600 */
 	current-speed = <9600>;
+
+	/* Enable as wakeup source */
 	wakeup-source;
-	wakeup-line = <28>;
+};
+
+&clk_lse {
+	/* Make sure LSE clock is enabled */
+	status = "okay";
 };