m68knommu: make BOOTPARAM setup common

Currently most of the m68knommu cpu/board setup files are handling
the setup of fixed boot parameters (via CONFIG_BOOTPARAM) themselves.
Move all this into the common setup code.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>