m68k: Remove M5485 boards

These board has not been converted to CONFIG_DM_PCI by the deadline.
Remove them.  As this is all of the CONFIG_M548x platforms as well,
remove that code.

Cc: TsiChung Liew <Tsi-Chung.Liew@nxp.com>
Signed-off-by: Tom Rini <trini@konsulko.com>