net: phy: Fix mask value write on gmii2rgmii converter speed register

To clear Speed Selection in MDIO control register(0x10),
ie, clear bits 6 and 13 to zero while keeping other bits same.
Before AND operation,The Mask value has to be perform with bitwise NOT
operation (ie, ~ operator)

This patch clears current speed selection before writing the
new speed settings to gmii2rgmii converter

Fixes: f411a616 ("net: phy: Add gmiitorgmii converter support")
Signed-off-by: NFahad Kunnathadi <fahad.kunnathadi@dexceldesigns.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/phy/xilinx_gmii2rgmii.c

@@ -44,7 +44,7 @@ static int xgmiitorgmii_read_status(struct phy_device *phydev)
 	priv->phy_drv->read_status(phydev);
 
 	val = mdiobus_read(phydev->mdio.bus, priv->addr, XILINX_GMII2RGMII_REG);
-	val &= XILINX_GMII2RGMII_SPEED_MASK;
+	val &= ~XILINX_GMII2RGMII_SPEED_MASK;
 
 	if (phydev->speed == SPEED_1000)
 		val |= BMCR_SPEED1000;