drivers: ethernet: phy: vsc8541: fixed build warnings

Fixed some build warnings in the driver from previous changes by
removing an unused variable and hooking up the cfg_link function.

Signed-off-by: Robert Hancock <robert.hancock@calian.com>

Author: robhancocksed

drivers/ethernet/phy/phy_microchip_vsc8541.c

@@ -284,7 +284,6 @@ static int phy_mc_vsc8541_cfg_link(const struct device *dev, enum phy_link_speed
 static int phy_mc_vsc8541_init(const struct device *dev)
 {
 	struct mc_vsc8541_data *data = dev->data;
-	struct mc_vsc8541_config *cfg = dev->config;
 	int ret;
 
 	data->active_page = -1;
@@ -489,6 +488,7 @@ static int phy_mc_vsc8541_write(const struct device *dev, uint16_t reg_addr, uin
 
 static DEVICE_API(ethphy, mc_vsc8541_phy_api) = {
 	.get_link = phy_mc_vsc8541_get_link,
+	.cfg_link = phy_mc_vsc8541_cfg_link,
 	.link_cb_set = phy_mc_vsc8541_link_cb_set,
 	.read = phy_mc_vsc8541_read,
 	.write = phy_mc_vsc8541_write,