Always rewrite EEPROM data and MAC addresses

Commit openwrt/openwrt@050621a introduced a new SPI-NAND driver for
MediaTek SoCs to Linux. It's the same driver we have already been
using in U-Boot and TF-A, so will be less maintainance work in future.

However, it turns out the new driver is particularly picky when it
comes to read data with broken OOB/ECC information, such as everything
written using the old driver **or even the stock factory partition**.

Hence, in order to run OpenWrt after commit openwrt/openwrt@050621a,
we need to read and write back the factory partition using the new
driver in order to make calibration data available again, as rewriting
fixes ECC errors left behind by previous firmware.

files/installer/install.sh

@@ -39,13 +39,8 @@ install_fix_factory() {
 		exit 1
 	fi
 
-	echo -n "found factory partition at offset $(printf %08x $((off))), "
-	if [ $((off)) -eq 0 ]; then
-		echo "ok."
-		return
-	fi
+	echo -n "found factory partition at offset $(printf %08x $((off))), rewriting..."
 
-	echo "fixing..."
 	dd if=$mtddev bs=$ebs skip=$skip count=1 of=/tmp/factory-fixed
 	mtd write /tmp/factory-fixed $mtddev
 	local magic="$(hexdump -v -n 2 -e '"%02x"' $mtddev)"
@@ -90,9 +85,9 @@ install_fix_macpart() {
 		exit 1
 	fi
 
-	[ $((blockoff)) -eq $((destoff)) ] && return
+	[ $((blockoff)) -eq $((destoff)) ] ||
+		echo "mac addresses block shifted by 0x$(printf %08x $((blockoff - destoff))), fixing."
 
-	echo "mac addresses block shifted by 0x$(printf %08x $((blockoff - destoff))), fixing."
 	dd if=$mtddev bs=$ebs skip=$skip count=1 of=/tmp/macs-fixed
 	mtd -p $destoff -l $ebs write /tmp/macs-fixed $mtddev
 }
@@ -140,10 +135,10 @@ install_prepare_ubi() {
 # backup mtd0...mtd2
 install_prepare_backup 2
 
-# make sure two mac addresses are store at correct offset in factory
+# rewrite two mac addresses are stored at correct offset in factory partition
 install_fix_macpart /dev/mtd2 0x60000 0x1fff4
 
-# make sure wifi eeprom starts at correct offset
+# make sure wifi eeprom starts at correct offset and rewrite to fix ECC
 install_fix_factory /dev/mtd2 "7622"
 
 echo "redundantly write bl2 into the first 4 blocks"