net: mscc: ocelot: drop workaround for forcing RX flow control

As phylink gained generic support for PHYs with rate matching via PAUSE
frames, the phylink_mac_link_up() method will be called with the maximum
speed and with rx_pause=true if rate matching is in use. This means that
setups with 2500base-x as the SERDES protocol between the MAC/PCS and
the PHY now work with no need for the driver to do anything special.

Tested with fsl-ls1028a-qds-7777.dts.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mscc/ocelot.c

@@ -872,10 +872,8 @@ void ocelot_phylink_mac_link_up(struct ocelot *ocelot, int port,
 		return;
 	}
 
-	/* Handle RX pause in all cases, with 2500base-X this is used for rate
-	 * adaptation.
-	 */
-	mac_fc_cfg |= SYS_MAC_FC_CFG_RX_FC_ENA;
+	if (rx_pause)
+		mac_fc_cfg |= SYS_MAC_FC_CFG_RX_FC_ENA;
 
 	if (tx_pause)
 		mac_fc_cfg |= SYS_MAC_FC_CFG_TX_FC_ENA |