m68k: use MMU version of setup.h for both MMU and non-MMU

The MMU version of setup.h can be used for all m68k platforms.
Without a single file "make headers_install" is broken for m68k
(since each of the sub-varients of setup.h are not installed).
Signed-off-by: Greg Ungerer <gerg@uclinux.org>

arch/m68k/include/asm/setup_no.h

-#ifdef __KERNEL__
-
-#include <asm/setup_mm.h>
-
-/* We have a bigger command line buffer. */
-#undef COMMAND_LINE_SIZE
-
-#endif  /*  __KERNEL__  */
-
-#define COMMAND_LINE_SIZE	512