m68k: merge non-mmu and mmu versions of m68k_ksyms.c

After cleaning up m68k_ksyms_no.c it is now strait forward to merge
the non-mmu and mmu versions of m68k_ksyms.c. The need for the extra
gcc functions is not strictly based on having an MMU or not. It is
based on the family the processor belongs too, so use an appropriate
conditional check.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>