ramips: update MAC address configuration for Buffalo WCR-1166DS

This patch converts MAC address configuration of Buffalo WCR-1166DS in
02_network to use the generic function of OpenWrt. And also, add
label_mac.

Signed-off-by: INAGAKI Hiroshi <musashino.open@gmail.com>

target/linux/ramips/mt76x8/base-files/etc/board.d/02_network

@@ -177,9 +177,9 @@ ramips_setup_macs()
 
 	case $board in
 	buffalo,wcr-1166ds)
-		local index="$(find_mtd_index "board_data")"
-		wan_mac="$(grep -m1 mac= "/dev/mtd${index}" | cut -d= -f2)"
+		wan_mac=$(mtd_get_mac_ascii board_data "mac")
 		lan_mac=$wan_mac
+		label_mac=$wan_mac
 		;;
 	cudy,wr1000|\
 	hilink,hlk-7628n|\