macvtap: Fix getPhysfn to get the PF of a direct attach network interface

macvtap: Fix getPhysfn to get the PF of a direct attach network interface

This patch renames getPhysfn to getPhysfnDev and adds code to get the
Physical function and Virtual Function index of the direct attach linkdev (if
the direct attach interface is a SRIOV VF). The idea is to send the port
profile message to a PF if the direct attach interface is a SRIOV VF.

Signed-off-by: Roopa Prabhu <roprabhu@cisco.com>
Signed-off-by: Christian Benvenuti <benve@cisco.com>
Signed-off-by: David Wang <dwang2@cisco.com>