m68k: allow ColdFire PCI bus on MMU and non-MMU configuration

Up to now we have only had support for the PCI bus when running the
ColdFire CPU family with the MMU enabled. The only reason for this was
the incomplete state of the IO remapping and access functions when
running with the MMU disabled.

Recent fixes and improvements to the ColdFire IO access code means we
can now support the PCI bus when running non-MMU enabled as well.
So modify the configuration support to allow it to be selected no matter
what choice of MMU mode is used.

Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
Reviewed-by: Angelo Dureghello <angelo@sysam.it>
Tested-by: Angelo Dureghello <angelo@sysam.it>