The enum for virNetDevVPort is declared in the header file
virnetdevvportprofile.h, but for some reason the impl is
in netdev_vport_profile_conf.c.

This causes a dep from src/util onto src/conf which is not
allowed. Move the enum impl into virnetdevvportprofile.c
to break the circle.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>