The nbd header uses __be32 and such types but doesn't actually include the
header that defines these things (linux/types.h); so let's include it.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>