lockd: discard nlmsvc_timeout

nlmsvc_timeout always has the same value as (nlm_timeout * HZ), so use
that in the one place that nlmsvc_timeout is used.

In truth it *might* not always be the same as nlmsvc_timeout is only set
when lockd is started while nlm_timeout can be set at anytime via
sysctl.  I think this difference it not helpful so removing it is good.

Also remove the test for nlm_timout being 0.  This is not possible -
unless a module parameter is used to set the minimum timeout to 0, and
if that happens then it probably should be honoured.

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