[PATCH] nfsd kconfig: select things at the closest tristate instead of bool

I noticed recently that my CONFIG_CRYPTO_MD5 turned into a y again instead
of m.  It turns out that CONFIG_NFSD_V4 is selecting it to be y even though
I've chosen to compile nfsd as a module.

In general when we have a bool sitting under a tristate it is better to
select things you need from the tristate rather than the bool since that
allows the things you select to be modules.

The following patch does it for nfsd.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>