feat: add M.2 B-key USB overlay for Radxa VMARC Q9075 IO

Signed-off-by: Songjun Li <lisongjun@radxa.com>

Author: RadxaSongjun

arch/arm64/boot/dts/qcom/overlays/Makefile

@@ -47,6 +47,7 @@ dtb-$(CONFIG_ARCH_QCOM) += qcs6490-radxa-cm-q64-rpi-cm5-io-cam0-imx219.dtbo \
 	qcs9075-i2c18.dtbo \
 	qcs9075-radxa-vmarc-q9075-io-cam1-imx577.dtbo \
 	qcs9075-radxa-vmarc-q9075-io-cam2-ov9281.dtbo \
+	qcs9075-radxa-vmarc-q9075-io-enable-b-key.dtbo \
 	qcs9075-radxa-vmarc-q9075-io-radxa-display-10fhd.dtbo \
 	qcs9075-radxa-vmarc-q9075-io-usb-peripheral.dtbo \
 	qcs9075-spi16-cs0-enc28j60.dtbo \

arch/arm64/boot/dts/qcom/overlays/qcs9075-radxa-vmarc-q9075-io-enable-b-key.dtso

@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/*
+ * Copyright (c) 2026 Radxa Computer (Shenzhen) Co., Ltd.
+ */
+
+/dts-v1/;
+/plugin/;
+
+#include <dt-bindings/gpio/gpio.h>
+
+/ {
+	metadata {
+		title = "Route USB to M.2 B-key";
+		compatible = "radxa,vmarc-q9075-io";
+		category = "misc";
+		exclusive = "switch-to-ekey-usb-regulator",
+			"pmm8654au_2_gpio11";
+		description = "Route USB from M.2 E-key to B-key for 4G modems.\nPMM8654AU_2 GPIO11=low";
+	};
+};
+
+&{/switch-to-ekey-usb-regulator} {
+	status = "disabled";
+};
+
+&pmm8654au_2_gpios {
+	bkey_usb_select_hog: bkey-usb-select-hog {
+		gpio-hog;
+		gpios = <11 GPIO_ACTIVE_HIGH>;
+		output-low;
+		line-name = "bkey-usb-select";
+	};
+};