arm64: dts: rockchip: add rfkill node for M.2 Key E WiFi on rock-5b

By default the GPIO pin that connects to the WiFi enable signal
inside the M.2 Key E slot is driven low, resulting in impossibility
to connect to any network. Add a DT node to expose it as an RFKILL
device, which lets the WiFi driver or userspace toggle it as
required.
Signed-off-by: Alexey Charkov <alchark@gmail.com>
Link: https://lore.kernel.org/r/20240106202650.22310-1-alchark@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3588-rock-5b.dts

@@ -58,6 +58,13 @@ fan: pwm-fan {
 		#cooling-cells = <2>;
 	};
 
+	rfkill {
+		compatible = "rfkill-gpio";
+		label = "rfkill-pcie-wlan";
+		radio-type = "wlan";
+		shutdown-gpios = <&gpio4 RK_PA2 GPIO_ACTIVE_HIGH>;
+	};
+
 	vcc3v3_pcie2x1l0: vcc3v3-pcie2x1l0-regulator {
 		compatible = "regulator-fixed";
 		enable-active-high;