m68k: consolidate the vmlinux.lds linker scripts

The merge of m68knommu left the linker scripts a little disorganized.
Some consistent naming and squashing two of scripts that just include
others can simplify things a lot.

So merge the two simple including scripts, and rename the nommu script
to be consistent with the existing m68k linker scripts.

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