board: sifli: sf32lb52_devkit_lcd: Add mbox in board device tree

Add mailbox in board devicetree, used in Bluetooth HCI driver.

Signed-off-by: Gang He <[email protected]>

Author: ganghe

boards/sifli/sf32lb52_devkit_lcd/sf32lb52_devkit_lcd.dts

@@ -21,6 +21,7 @@
 		zephyr,code-partition = &code;
 		zephyr,console = &usart1;
 		zephyr,shell-uart = &usart1;
+		zephyr,bt-hci = &mailbox;
 	};
 
 	buttons {
@@ -119,3 +120,8 @@
 	pinctrl-0 = <&usart1_default>;
 	pinctrl-names = "default";
 };
+
+&mailbox {
+	status = "okay";
+};
+