net: bcmgenet: Clear ID_MODE_DIS in EXT_RGMII_OOB_CTRL when not needed

Outdated Raspberry Pi 4 firmware might configure the external PHY as
rgmii although the kernel currently sets it as rgmii-rxid. This makes
connections unreliable as ID_MODE_DIS is left enabled. To avoid this,
explicitly clear that bit whenever we don't need it.

Fixes: da38802211cc ("net: bcmgenet: Add RGMII_RXID support")
Signed-off-by: Nicolas Saenz Julienne <[e-mail]>
Acked-by: Florian Fainelli <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/broadcom/genet/bcmmii.c

···
 	 */
 	if (priv->ext_phy) {
 		reg = bcmgenet_ext_readl(priv, EXT_RGMII_OOB_CTRL);
+		reg &= ~ID_MODE_DIS;
 		reg |= id_mode_dis;
 		if (GENET_IS_V1(priv) || GENET_IS_V2(priv) || GENET_IS_V3(priv))
 			reg |= RGMII_MODE_EN_V123;