ixgbevf: Move API negotiation function into mac_ops

This patch moves API negotiation into mac_ops.  The general idea here is
that with HyperV on the way we need to make certain that anything that will
have different versions between HyperV and a standard VF needs to be
abstracted enough so that we can have a separate function between the two
so we can avoid changes in one breaking something in the other.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>