sfc: add ndo_set_vf_link_state() function for EF10

Exercised with
"ip link set <PF intf> vf <vf_i> state {auto|enable|disable}"
Sets the reporting policy for VF link state to either
 - mirror physical link state
 - always up
 - always down

get VF link state mode in efx_ef10_sriov_get_vf_config

Exercised by
"ip link show <PF intf>";
output will include a line like
vf 0 MAC 12:34:56:78:9a:bc, link-state auto

Signed-off-by: Shradha Shah <sshah@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/sfc/sriov.c b/drivers/net/ethernet/sfc/sriov.c
index d4b7445..6c5edbd 100644
--- a/drivers/net/ethernet/sfc/sriov.c
+++ b/drivers/net/ethernet/sfc/sriov.c
@@ -58,3 +58,15 @@
 	else
 		return -EOPNOTSUPP;
 }
+
+int efx_sriov_set_vf_link_state(struct net_device *net_dev, int vf_i,
+				int link_state)
+{
+	struct efx_nic *efx = netdev_priv(net_dev);
+
+	if (efx->type->sriov_set_vf_link_state)
+		return efx->type->sriov_set_vf_link_state(efx, vf_i,
+							  link_state);
+	else
+		return -EOPNOTSUPP;
+}