m68knommu: disable cache early in startup for ColdFire

Disbale the CPU cache really early in the ColdFire startup code. We set
up some variables for RAM sizing and we want to make they stick in RAM.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>