MAKEALL: rename coldfire list to m68k to match arch

The m68k tree is the only one where `./MAKEALL <arch>` does not work.
So rename the existing coldfire list in the MAKEALL script to m68k, and
add an alias from coldfire to m68k.  This makes scripting around MAKEALL
easier.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>