arm64: dts: mt7622: fix no more console output on rfb1

No default serial console on boot.
Fix this by using a 'stdout-path' property that points to the device.

Fixes: c0d9f9ad4f76 ("arm64: dts: mt7622: add earlycon to mt7622-rfb1 board")
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>
[mb: Fix commit message]
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

arch/arm64/boot/dts/mediatek/mt7622-rfb1.dts

@@ -17,8 +17,13 @@
 	model = "MediaTek MT7622 RFB1 board";
 	compatible = "mediatek,mt7622-rfb1", "mediatek,mt7622";
 
+	aliases {
+		serial0 = &uart0;
+	};
+
 	chosen {
-		bootargs = "earlycon=uart8250,mmio32,0x11002000 console=ttyS0,115200n1 swiotlb=512";
+		stdout-path = "serial0:115200n8";
+		bootargs = "earlycon=uart8250,mmio32,0x11002000 swiotlb=512";
 	};
 
 	cpus {