sfc: Store port number in net_device::dev_id

This exposes the port number to userland through sysfs.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/sfc/siena.c b/drivers/net/sfc/siena.c
index 7ecd255..f2b1e61 100644
--- a/drivers/net/sfc/siena.c
+++ b/drivers/net/sfc/siena.c
@@ -222,7 +222,7 @@
 	}
 
 	efx_reado(efx, &reg, FR_AZ_CS_DEBUG);
-	efx->port_num = EFX_OWORD_FIELD(reg, FRF_CZ_CS_PORT_NUM) - 1;
+	efx->net_dev->dev_id = EFX_OWORD_FIELD(reg, FRF_CZ_CS_PORT_NUM) - 1;
 
 	efx_mcdi_init(efx);