net: zynq_gem: Initialize phyreg variable

In case of phyread()/phy_setup_op() timeout code is working with
uninitialized phyreg variable. Initialize this variable to make sure
that code it not working with random value.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

drivers/net/zynq_gem.c

@@ -244,7 +244,7 @@ static int phywrite(struct zynq_gem_priv *priv, u32 phy_addr,
 static int phy_detection(struct udevice *dev)
 {
 	int i;
-	u16 phyreg;
+	u16 phyreg = 0;
 	struct zynq_gem_priv *priv = dev->priv;
 
 	if (priv->phyaddr != -1) {