net: xilinx: axi_emac: Fix endless loop when no PHYs are connected

The index used to iterate over the possible PHYs in axiemac_phy_init was an
unsigned int and decremented. Therefor it was always >= 0 and never exited
the loop.

Signed-off-by: Patrick van Gelder <patrick.vangelder@nl.bosch.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/drivers/net/xilinx_axi_emac.c b/drivers/net/xilinx_axi_emac.c
index d0683db..2cd5596 100644
--- a/drivers/net/xilinx_axi_emac.c
+++ b/drivers/net/xilinx_axi_emac.c
@@ -244,7 +244,8 @@
 static int axiemac_phy_init(struct udevice *dev)
 {
 	u16 phyreg;
-	u32 i, ret;
+	int i;
+	u32 ret;
 	struct axidma_priv *priv = dev_get_priv(dev);
 	struct axi_regs *regs = priv->iobase;
 	struct phy_device *phydev;