Revert "Use GPT for raw images"

This reverts commit 6b69df91a5.

tools-image/build-arm-image.sh

@@ -345,8 +345,6 @@ partprobe
 
 echo ">> Writing image and partition table"
 dd if=/dev/zero of="${output_image}" bs=1024000 count="${size}" || exit 1
-# make it gpt
-echo "label: gpt" | sfdisk "${output_image}"
 if [ "$model" == "rpi64" ]; then 
     sgdisk -n 1:8192:+96M -c 1:EFI -t 1:0c00 ${output_image}
 else
@@ -382,7 +380,7 @@ export device="/dev/mapper/${device}"
 
 partprobe
 
-kpartx -vag $DRIVE
+kpartx -va $DRIVE
 
 echo ">> Populating partitions"
 efi=${device}p1