net: dm: fec: Fix time unit error in phy-reset-duration

The DT binding says that phy-reset-duration is in ms, but the driver
currently uses udelay().

Switch to mdelay() to fix this.

Signed-off-by: Martin Fuzzey <martin.fuzzey@flowbird.group>
Reviewed-by: Michael Trimarchi <michael@amarulasolutions.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/drivers/net/fec_mxc.c b/drivers/net/fec_mxc.c
index dac07b6..a1295fc 100644
--- a/drivers/net/fec_mxc.c
+++ b/drivers/net/fec_mxc.c
@@ -1254,7 +1254,7 @@
 	debug("fec_gpio_reset: fec_gpio_reset(dev)\n");
 	if (dm_gpio_is_valid(&priv->phy_reset_gpio)) {
 		dm_gpio_set_value(&priv->phy_reset_gpio, 1);
-		udelay(priv->reset_delay);
+		mdelay(priv->reset_delay);
 		dm_gpio_set_value(&priv->phy_reset_gpio, 0);
 	}
 }