boards: silabs: siwx91x: Add support for Bluetooth

Report Bluetooth HCI declaration in the board definitions.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>

boards/silabs/radio_boards/siwx917_rb4338a/siwx917_rb4338a.dts

@@ -20,6 +20,7 @@
 		zephyr,code-partition = &code_partition;
 		zephyr,console = &ulpuart;
 		zephyr,shell-uart = &ulpuart;
+		zephyr,bt-hci = &bt_hci0;
 	};
 
 	aliases {
@@ -85,3 +86,7 @@
 		};
 	};
 };
+
+&bt_hci0 {
+	status = "okay";
+};

boards/silabs/radio_boards/siwx917_rb4338a/siwx917_rb4338a.yaml

@@ -9,6 +9,7 @@ toolchain:
   - gnuarmemb
   - xtools
 supported:
+  - bluetooth
   - dma
   - entropy
   - flash

dts/arm/silabs/siwg917.dtsi

@@ -29,6 +29,11 @@
 		reg = <0x00000000 DT_SIZE_K(191)>;
 	};
 
+	bt_hci0: bt_hci {
+		compatible = "silabs,siwx91x-bt-hci";
+		status = "disabled";
+	};
+
 	soc {
 		clock0: clock@46000000 {
 			compatible = "silabs,siwx91x-clock";