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: 55cfeb3 ("net: dsa: bcm_sf2: add function finding RGMII register")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/bcm_sf2.c

@@ -821,11 +821,9 @@ static void bcm_sf2_sw_mac_link_up(struct dsa_switch *ds, int port,
 	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)
 			offset = CORE_STS_OVERRIDE_GMIIP_PORT(port);
@@ -836,6 +834,7 @@ static void bcm_sf2_sw_mac_link_up(struct dsa_switch *ds, int port,
 		    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);