m68knommu: use common interrupt controller code for older ColdFire CPU's

The old ColdFire CPU's (5206, 5307, 5407, 5249 etc) use a simple
interrupt controller. Use common setup code for them. This addition
means that all ColdFire CPU's now have some specific type of interrupt
controller code.

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