net: ethernet: ti: am65-cpsw: fix rmii 100Mbit link mode

In RMII link mode it's required to set bit 15 IFCTL_A in MAC_SL MAC_CONTROL
register to enable support for 100Mbit link speed.

Fixes: 93a76530 ("net: ethernet: ti: introduce am65x/j721e gigabit eth subsystem driver")
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/am65-cpsw-nuss.c

@@ -174,6 +174,8 @@ void am65_cpsw_nuss_adjust_link(struct net_device *ndev)
 		if (phy->speed == 10 && phy_interface_is_rgmii(phy))
 			/* Can be used with in band mode only */
 			mac_control |= CPSW_SL_CTL_EXT_EN;
+		if (phy->speed == 100 && phy->interface == PHY_INTERFACE_MODE_RMII)
+			mac_control |= CPSW_SL_CTL_IFCTL_A;
 		if (phy->duplex)
 			mac_control |= CPSW_SL_CTL_FULLDUPLEX;