veth: added hint to load vzethdev

In case vzctl fails to configure veth device because kernel returns
ENOTTY from VETHCTL_VE_HWADDR ioctl(), this means kernel doesn't know
anything about veth. Most common reason (for recent kernel) is that
kernel module is not loaded -- give a user a hint about it.

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
1 file changed