sfc: Move the current VF state from efx_nic into siena_nic_data

This patch series provides a base and cleanup for the
upcoming EF10 SRIOV support.

This patch moves the VF state into siena_nic_data as a basis to
save the VF state based on nic type.

Signed-off-by: Shradha Shah <sshah@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>