m68knommu: move ColdFire PIT timer base addresses

The PIT hardware timer module used in some ColdFire CPU's is not always
addressed relative to an IPSBAR register. Parts like the ColdFire 5207 and
5208 have fixed peripheral addresses. So lets not define the register
addresses of the PIT relative to an IPSBAR definition. Move the base
address definitions into the per-part headers. This is a lot more consistent
since all the other peripheral base addresses are defined in the per-part
header files already.

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