sfc: Change type of efx_nic::nic_data to struct falcon_nic_data *

Remove redundant casts and variable.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index be09180..f4757e1 100644
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -705,7 +705,7 @@
 
 	unsigned n_rx_nodesc_drop_cnt;
 
-	void *nic_data;
+	struct falcon_nic_data *nic_data;
 
 	struct mutex mac_lock;
 	int port_enabled;