Replace CONFIG_8xx and CONFIG_MCF532x to CONFIG_MII_INIT in
cmd_init.c. Add CONFIG_MII_INIT to board configuration files
that use mii_init() in cmd_init.c.

Signed-off-by: TsiChung Liew <Tsi-Chung.Liew@freescale.com>
Acked-by: Ben Warren <biggerbadderben@gmail.com>