mediatek: u7623-02: enable early console also in legacy image

Append 'earlycon=uart8250,mmio32,0x11004000' to the boot arguments
embedded in device-tree in order to enable early console on the
UniElec U7623 board when using the vendor/stock bootloader.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

target/linux/mediatek/dts/mt7623a-unielec-u7623-02-emmc-512m.dts

@@ -11,7 +11,7 @@
 	compatible = "unielec,u7623-02-emmc-512m", "unielec,u7623-02", "mediatek,mt7623";
 
 	chosen {
-		bootargs = "root=/dev/mmcblk0p2 rootfstype=squashfs,f2fs console=ttyS0,115200 blkdevparts=mmcblk0:3M@6M(recovery),256M@9M(root)";
+		bootargs = "earlycon=uart8250,mmio32,0x11004000 console=ttyS0,115200 blkdevparts=mmcblk0:3M@6M(recovery),256M@9M(root) rootfstype=squashfs root=/dev/mmcblk0p2";
 	};
 
 	memory@80000000 {