LU-15440 lnet: lnet_peer_data_present() memory leak

LU-15440 lnet: lnet_peer_data_present() memory leak

If the ping buffer has nnis <= 1 then the ref on the ping buffer does
not get dropped. This causes a memory leak.

Test-Parameters: trivial testlist=sanity-lnet
Signed-off-by: Chris Horn <chris.horn@hpe.com>
Change-Id: I5e3c651ffecbe4f8860afb86770cecef23ebe862
Reviewed-on: https://review.whamcloud.com/46052
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Andriy Skulysh <andriy.skulysh@hpe.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Alexey Lyashkov <alexey.lyashkov@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>