NFSD: Replace use of NFSD_MAY_LOCK in nfsd4_lock()

NFSv4 LOCK operations should not avoid the set of authorization
checks that apply to all other NFSv4 operations. Also, the
"no_auth_nlm" export option should apply only to NLM LOCK requests.
It's not necessary or sensible to apply it to NFSv4 LOCK operations.

Instead, set no permission bits when calling fh_verify(). Subsequent
stateid processing handles authorization checks.

Reported-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>