m68k: remove rpxlite stuff

The CONFIG_RPXLITE is not defined anywhere, which means that this board is not
supported anyway, and we can clean-up commproc.h a little.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: linux-pcmcia@lists.infradead.org
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: linux-m68k@lists.linux-m68k.org
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>