m68knommu: clean up ColdFire cache control code

The cache control code for the ColdFire CPU's is a big ugly mess
of "#ifdef"ery liberally coated with bit constants. Clean it up.

The cache controllers in the various ColdFire parts are actually quite
similar. Just differing in some bit flags and options supported. Using
the header defines now in place it is pretty easy to factor out the
small differences and use common setup and flush/invalidate code.

I have preserved the cache setups as they where in the old code
(except where obviously wrong - like in the case of the 5249). Following
from this it should be easy now to extend the possible setups used on
the CACHE controllers that support split cacheing or copy-back or
write through options.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>