Convert CONFIG_MII_INIT to Kconfig

This converts the following to Kconfig:
   CONFIG_MII_INIT

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/eb_cpu5282_defconfig b/configs/eb_cpu5282_defconfig
index a1aee40..ae1329c 100644
--- a/configs/eb_cpu5282_defconfig
+++ b/configs/eb_cpu5282_defconfig
@@ -23,6 +23,7 @@
 CONFIG_CMD_DHCP=y
 CONFIG_BOOTP_BOOTFILESIZE=y
 CONFIG_CMD_MII=y
+CONFIG_MII_INIT=y
 CONFIG_CMD_DATE=y
 CONFIG_ENV_ADDR=0xFF040000
 CONFIG_SYS_FAULT_ECHO_LINK_DOWN=y