net: dsa: bcm_sf2: Fix bcm_sf2_reg_rgmii_cntrl() call for non-RGMII port

We cannot call bcm_sf2_reg_rgmii_cntrl() for a port that is not RGMII,
yet we do that in bcm_sf2_sw_mac_link_up() irrespective of the port's
interface. Move that read until we have properly qualified the PHY
interface mode. This avoids triggering a warning on 7278 platforms that
have GMII ports.

Fixes: 55cfeb396965 ("net: dsa: bcm_sf2: add function finding RGMII register")
Signed-off-by: Florian Fainelli <[e-mail]>
Acked-by: Rafał Miłecki <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/dsa/bcm_sf2.c

···
 	bcm_sf2_sw_mac_link_set(ds, port, interface, true);
 
 	if (port != core_readl(priv, CORE_IMP0_PRT_ID)) {
-		u32 reg_rgmii_ctrl;
+		u32 reg_rgmii_ctrl = 0;
 		u32 reg, offset;
-
-		reg_rgmii_ctrl = bcm_sf2_reg_rgmii_cntrl(priv, port);
 
 		if (priv->type == BCM4908_DEVICE_ID ||
 		    priv->type == BCM7445_DEVICE_ID)
···
 		    interface == PHY_INTERFACE_MODE_RGMII_TXID ||
 		    interface == PHY_INTERFACE_MODE_MII ||
 		    interface == PHY_INTERFACE_MODE_REVMII) {
+			reg_rgmii_ctrl = bcm_sf2_reg_rgmii_cntrl(priv, port);
 			reg = reg_readl(priv, reg_rgmii_ctrl);
 			reg &= ~(RX_PAUSE_EN | TX_PAUSE_EN);