qemu.tests: Rename mac_ip_filter to interface_mac_ip_filter in multi_vms...

....nics.py

mac_ip_filter already used to save RE string to filter mac and ip.
But in multi_vms_nics.py, we need RE string to filter interface, mac and ip.
So create a new paramter interface_mac_ip_filter.

Signed-off-by: Feng Yang <fyang@redhat.com>