arm64: dts: mediatek: mt7988a-bpi-r4: add overlay to disable pcie2

Some Modems like FM350-GL require pcie disabled on m.2 key-b slot (CN16)
to work properly.

Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
---
based on overlay file from user Andrew
https://forum.banana-pi.org/t/fm350-gl-and-be14-finally-works-on-bpi-r4/19170/40

Author: frank-w

arch/arm64/boot/dts/mediatek/Makefile

@@ -31,6 +31,7 @@ dtb-$(CONFIG_ARCH_MEDIATEK) += mt7987a-bananapi-bpi-r4-lite.dtb
 dtb-$(CONFIG_ARCH_MEDIATEK) += mt7988a-bananapi-bpi-r4.dtb
 dtb-$(CONFIG_ARCH_MEDIATEK) += mt7988a-bananapi-bpi-r4-2g5.dtb
 dtb-$(CONFIG_ARCH_MEDIATEK) += mt7988a-bananapi-bpi-r4-emmc.dtbo
+dtb-$(CONFIG_ARCH_MEDIATEK) += mt7988a-bananapi-bpi-r4-nopcie2.dtbo
 dtb-$(CONFIG_ARCH_MEDIATEK) += mt7988a-bananapi-bpi-r4-pro-4e.dtb
 dtb-$(CONFIG_ARCH_MEDIATEK) += mt7988a-bananapi-bpi-r4-pro-8x.dtb
 dtb-$(CONFIG_ARCH_MEDIATEK) += mt7988a-bananapi-bpi-r4-pro-cn15.dtbo

arch/arm64/boot/dts/mediatek/mt7988a-bananapi-bpi-r4-nopcie2.dtso

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/*
+ * Copyright (C) 2023 MediaTek Inc.
+ * Author: Frank Wunderlich <frank-w@public-files.de>
+ */
+
+/dts-v1/;
+/plugin/;
+
+#include <dt-bindings/gpio/gpio.h>
+
+/ {
+	compatible = "bananapi,bpi-r4", "mediatek,mt7988a";
+};
+
+&{/soc/pcie@11280000} {
+	status = "disabled";
+};