lockd: fix FILE_LOCKING=n build error

lockd: fix FILE_LOCKING=n build error

lockd/svclock.c is missing a header file <linux/fs.h>.

<linux/fs.h> is missing a definition of locks_release_private()
for the config case of FILE_LOCKING=n, causing a build error:

fs/lockd/svclock.c:330: error: implicit declaration of function 'locks_release_private'

lockd without FILE_LOCKING doesn't make sense, so make LOCKD and LOCKD_V4
depend on FILE_LOCKING, and make NFS depend on FILE_LOCKING.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>