m68knommu: make ColdFire M532x platform support more v3 generic

The M532x CPU platform support can be used on more ColdFire CPU families
than just the 532x types. So rename and reconfigure it to reflect that.
The ColdFire 537x family has virtualy identical internals to the 532x,
and so it will be able to share this code when we add support for them.

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