LU-16145 lnet: Honor peer timeout of zero

LU-16145 lnet: Honor peer timeout of zero

Zero is a valid value for the peer_timeout parameter (it is supposed
to disable the LNet Peer Health feature used on routers), but DLC
treats zero as uninitialized and assigns the default peer timeout
instead.

Test-Parameters: trivial testlist=sanity-lnet
HPE-bug-id: LUS-11233
Signed-off-by: Chris Horn <chris.horn@hpe.com>
Change-Id: I66f45ddf282757f46c0169ae0e725e56234d3d89
Reviewed-on: https://review.whamcloud.com/48489
Reviewed-by: Frank Sehr <fsehr@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>