mediatek: mt7623: bpi-r2: add ethernet alias to device tree

Add ethernet0 alias in device tree to make U-Boot inherit the Ethernet
mac address (set via environment variable 'ethaddr') down to Linux.

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

target/linux/mediatek/patches-5.10/163-dts-mt7623-bpi-r2-ethernet-alias.patch

@@ -0,0 +1,10 @@
+--- a/arch/arm/boot/dts/mt7623n-bananapi-bpi-r2.dts
++++ b/arch/arm/boot/dts/mt7623n-bananapi-bpi-r2.dts
+@@ -15,6 +15,7 @@
+ 
+ 	aliases {
+ 		serial2 = &uart2;
++		ethernet0 = &gmac0;
+ 		mmc0 = &mmc0;
+ 		mmc1 = &mmc1;
+ 		led-boot = &led_system_green;