m68k/m68knommu: merge the MMU and non-MMU traps.h

The MMU and non-MMU versions of traps.h are virtually identical,
merge them into a single file.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>