libvirt.xml: fix IP address declaration
libvirt.xml: fix IP address declaration

There is no longer different one for DispVM savefile preparation - there
is no DispVM savefile anymore.

marmarek/qubes-core-admin,woju/qubes-core-admin,QubesOS/qubes-core-admin,woju/qubes-core-admin,QubesOS/qubes-core-admin,woju/qubes-core-admin,woju/qubes-core-admin,marmarek/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin