[][MAC80211][infra][Update dts for mt76 to support flash mode]

[Description]
Add slot0 in dts for mt76 to support flash mode

[Release-log]
N/A

Change-Id: I3ee413070f2a93090355dcdae1f7e742cbab321f
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7077950
diff --git a/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7988.dtsi b/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7988.dtsi
index 3dd999f..46f0708 100644
--- a/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7988.dtsi
+++ b/target/linux/mediatek/files-5.4/arch/arm64/boot/dts/mediatek/mt7988.dtsi
@@ -582,6 +582,10 @@
 			#interrupt-cells = <1>;
 			interrupt-controller;
 		};
+
+		slot0: pcie@0,0 {
+			reg = <0x0000 0 0 0 0>;
+		};
 	};
 
 	pcie1: pcie@11310000 {