liquidio: switchdev support for LiquidIO NIC

Enable switchdev for SRIOV capable LiquidIO NIC. It registers
a representor netdev (with switchdev_ops) for each SRIOV VF created.
It also has changes to send representor interface configurations like
admin state and MTU to LiquidIO firmware and to retrieve HW counted
VF stats for VF representor.

Signed-off-by: Vijaya Mohan Guvva <vijaya.guvva@cavium.com>
Signed-off-by: Satanand Burla <satananda.burla@cavium.com>
Signed-off-by: Raghu Vatsavayi <raghu.vatsavayi@cavium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>