zynq: fix detection of the zybo board

The board_name was being tested for "xlnx,zynq-zybo",
but the .dts compatible string is "digilent,zynq-zybo"

Also, sorted the boards alphabetically, and added an
error message for unsupported boards

Signed-off-by: Luis Araneda <luaraneda@gmail.com>

target/linux/zynq/base-files/etc/board.d/02_network

@@ -6,9 +6,14 @@
 board_config_update
 
 case "$(board_name)" in
-	xlnx,zynq-zc702|xlnx,zynq-zed|xlnx,zynq-zybo)
+digilent,zynq-zybo | \
+xlnx,zynq-zc702 | \
+xlnx,zynq-zed)
 	ucidef_set_interface_lan 'eth0'
 	;;
+*)
+	echo "Unsupported hardware. Network interfaces not intialized"
+	;;
 esac
 
 board_config_flush