The ironic_dnsmasq config for ironic inspector uses the internal VIP for
the TFTP server address DHCP option. This is not going to work,
since HAProxy is not configured to forward TFTP, and does not support
UDP forwarding anyway. The config should use the api_interface IP for
the host running ironic_dnsmasq.

Change-Id: I56a0d46e9b528041cacea7196a525891ed5922f0
Closes-Bug: #1761815