By now, ironic-dnsmasq has default bootfile pxelinux.0,
which is correct only for x86.
Adding ironic_dnsmasq_boot_file parameter to globals.yml
to make it configuable.
For example: /etc/kolla/globals.yml
ironic_dnsmasq_boot_file: "debian-installer/arm64/bootnetaa64.efi"

Change-Id: I6eb57702d4dad549ef8c999c1c82e577f316d8d6