m68knommu: limit interrupts supported by ColdFire intc-2 driver

The intc-2 interrupt controller on some ColdFire CPUs has a set range of
interrupts its supports (64 through 128 or 192 depending on model). We
shouldn't be setting this handler for every possible interrupt from 0 to
255. Set more appropriate limits, and this means we can drop the interrupt
number check in the mask and unmask routines.

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