m68k: ColdFire V4e MMU context support code

Add code to manage the context's of the ColdFire V4e MMU. This code is
mostly taken from the Freescale 2.6.35 kernel BSP for MMU enabled ColdFire.

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>