Fix partition table mismatch

gen_disks expects swap to be present, yet we disabled it in
alpine_install.

gen_disks.sh

@@ -15,7 +15,7 @@ for dir in output/*/; do
 	pushd $dir
 	cp --preserve=mode,ownership "$origdir/dummydisk.img" "./disk.img"
 	loop="$(losetup --partscan --show --find ./disk.img)"
-	mount -t ext4 "${loop}p3" "$mount"
+	mount -t ext4 "${loop}p2" "$mount"
 	while read what where; do
 		cp "$what" "$mount$where"
 	done << END