Load lvm module in grub mode

If the DMS live ISO loopback boot runs on a machine
that has root (/) on LVM we need to load lvm in grub
to be able to read from the root of the toplevel
volume

grub.d/99_migration

@@ -74,6 +74,7 @@ if grub_file_is_not_garbage "${migration_iso}"; then
             "/@/boot/grub2/x86_64-efi"
         printf "    insmod loopback\n"
     fi
+    printf "    insmod lvm\n"
     printf "    insmod %s\n" "${image_fs_type}"
     printf "    search --no-floppy --fs-uuid --set=root %s\n" "${image_fs_uuid}"
     printf "    set isofile='%s'\n" \