m68k: add ColdFire 54xx CPU MMU memory init code

Add code to the 54xx ColdFire CPU init to setup memory ready for the m68k
paged memory start up.

Some of the RAM variables that were specific to the non-mmu code paths
now need to be used during this setup, so when CONFIG_MMU is enabled.
Move these out of page_no.h and into page.h.

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