cgroups: remove duplicate include

commit e6a1105b ("cgroups: subsystem module loading interface") and commit
c50cc752 ("sched, cgroups: Fix module export") result in duplicate
including of module.h

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>