can: slcan: export slcan_ethtool_ops and remove slcan_set_ethtool_ops()

The function slcan_set_ethtool_ops() does one thing: populate
net_device::ethtool_ops. Instead, it is possible to directly assign
this field and remove one function call and slightly reduce the object
size. To do so, export slcan_ethtool_ops so it becomes visible to
sclan-core.c.

This patch reduces the footprint by 14 bytes:

| $ ./scripts/bloat-o-meter drivers/net/can/slcan/slcan.{old,new}.o
| drivers/net/can/slcan/slcan.o
| add/remove: 0/1 grow/shrink: 1/0 up/down: 15/-29 (-14)
| Function                                     old     new   delta
| slcan_open                                  1010    1025     +15
| slcan_set_ethtool_ops                         29       -     -29
| Total: Before=11115, After=11101, chg -0.13%

Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/all/20220727104939.279022-2-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/slcan/slcan-core.c

@@ -866,8 +866,8 @@ static struct slcan *slc_alloc(void)
 
 	snprintf(dev->name, sizeof(dev->name), "slcan%d", i);
 	dev->netdev_ops = &slc_netdev_ops;
+	dev->ethtool_ops = &slcan_ethtool_ops;
 	dev->base_addr  = i;
-	slcan_set_ethtool_ops(dev);
 	sl = netdev_priv(dev);
 
 	/* Initialize channel control data */

drivers/net/can/slcan/slcan-ethtool.c

@@ -52,14 +52,9 @@ static int slcan_get_sset_count(struct net_device *netdev, int sset)
 	}
 }
 
-static const struct ethtool_ops slcan_ethtool_ops = {
+const struct ethtool_ops slcan_ethtool_ops = {
 	.get_strings = slcan_get_strings,
 	.get_priv_flags = slcan_get_priv_flags,
 	.set_priv_flags = slcan_set_priv_flags,
 	.get_sset_count = slcan_get_sset_count,
 };
-
-void slcan_set_ethtool_ops(struct net_device *netdev)
-{
-	netdev->ethtool_ops = &slcan_ethtool_ops;
-}

drivers/net/can/slcan/slcan.h

@@ -13,6 +13,7 @@
 
 bool slcan_err_rst_on_open(struct net_device *ndev);
 int slcan_enable_err_rst_on_open(struct net_device *ndev, bool on);
-void slcan_set_ethtool_ops(struct net_device *ndev);
+
+extern const struct ethtool_ops slcan_ethtool_ops;
 
 #endif /* _SLCAN_H */