Staging: Dream: separate Kconfig/Makefile into subdirectory

Separate Kconfig/Makefile glue from dream into subdirectory. I plan to
add few more drivers, and changing staging/Makefile each time sounds
like inviting conflicts.

Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>