m68k: add ColdFire paging exception handling code

Add code to traps.c to handle MMU exceptions for the ColdFire.
Most of this code is from the 2.6.25 kernel BSP code released by
Freescale.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Matt Waddel <mwaddel@yahoo.com>
Acked-by: Kurt Mahan <kmahan@xmission.com>