LU-15039 lnet: Fix reference leak in lnet_parse

LU-15039 lnet: Fix reference leak in lnet_parse

We need to drop the reference taken by lnet_nid2peerni_locked() if we
determine that we need to drop the message because of asymmetric
route.

Lustre-change: https://review.whamcloud.com/45067
Lustre-commit: e69eca08bce47bf85b3c011598e360a2468019b5

Test-Parameters: trivial
HPE-bug-id: LUS-9186
Fixes: 955080c3ae ("LU-13779 lnet: Correct asymmetric route detection")
Signed-off-by: Chris Horn <chris.horn@hpe.com>
Change-Id: I799c9522b1ce5f4caffc5848a829995e5b5484e7
Reviewed-on: https://review.whamcloud.com/48378
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Frank Sehr <fsehr@whamcloud.com>
Reviewed-by: Alexandre Ioffe <aioffe@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>