util: remove useless checks for IFLA_VF_MAX

util: remove useless checks for IFLA_VF_MAX

IFLA_VF_MAX was introduced to the Linux kernel in 2.6.35, and was even
backported to the RHEL*6* 2.6.32 kernel downstream, so it is present
in all supported versions of all Linux distros that libvirt builds
on. Additionally, it can't be conditionally compiled out of a
kernel. There is no reason to conditionalize any piece of code on
presence of IFLA_VF_MAX - if the platform is Linux, it is supported.

Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>