configs: colibri-imx6ull/-emmc: use micrel ksz8xxx phy driver

Use the Micrel KSZ8xxx specific Ethernet PHY driver rather than the
generic one.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
diff --git a/configs/colibri-imx6ull_defconfig b/configs/colibri-imx6ull_defconfig
index c601e96..b75e217 100644
--- a/configs/colibri-imx6ull_defconfig
+++ b/configs/colibri-imx6ull_defconfig
@@ -77,6 +77,7 @@
 CONFIG_MTD_UBI_FASTMAP=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_MICREL=y
+CONFIG_PHY_MICREL_KSZ8XXX=y
 CONFIG_DM_ETH=y
 CONFIG_FEC_MXC=y
 CONFIG_MII=y