Fix $sduuid to be of format UUID=uuid

- this issue was introduced by commit 7e9ebe1
- the variable sduuid is supposed to start with "UUID="
- fixed now by prepending UUID= to $sduuid, if the "raw" $sduuid is not empty

closes AR-1611

packages/bsp/common/usr/sbin/armbian-install

@@ -69,6 +69,7 @@ sdblkid=$(blkid -o full /dev/mmcblk*p1 | grep -v "$root_partition_device")
 [[ -z $sdblkid ]] && sdblkid=$(blkid -o full /dev/mmcblk*p1)
 # 3 - Extract the UUID from $sdblkid via regex:
 sduuid=$(echo "$sdblkid" | sed -nE 's/^.*[[:space:]]UUID="([0-9a-zA-Z-]*)".*/\1/p')
+[[ -n $sduuid ]] && sduuid="UUID=${sduuid}"
 
 #recognize EFI
 [[ -d /sys/firmware/efi ]] && DEVICE_TYPE="uefi"