r8169: fix firmware not resetting tp->ocp_base

Typically the firmware takes care that tp->ocp_base is reset to its
default value. That's not the case (at least) for RTL8117.
As a result subsequent PHY access reads/writes the wrong page and
the link is broken. Fix this be resetting tp->ocp_base explicitly.

Fixes: 229c1e0d ("r8169: load firmware for RTL8168fp/RTL8117")
Reported-by: Aaron Ma <mapengyu@gmail.com>
Tested-by: Aaron Ma <mapengyu@gmail.com>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/r8169_main.c

@@ -2114,8 +2114,11 @@ static void rtl_release_firmware(struct rtl8169_private *tp)
 void r8169_apply_firmware(struct rtl8169_private *tp)
 {
 	/* TODO: release firmware if rtl_fw_write_firmware signals failure. */
-	if (tp->rtl_fw)
+	if (tp->rtl_fw) {
 		rtl_fw_write_firmware(tp, tp->rtl_fw);
+		/* At least one firmware doesn't reset tp->ocp_base. */
+		tp->ocp_base = OCP_STD_PHY_BASE;
+	}
 }
 
 static void rtl8168_config_eee_mac(struct rtl8169_private *tp)