LU-13454 lnet: Handle health stats for reply to optimized GET

LU-13454 lnet: Handle health stats for reply to optimized GET

The LNet messages used for replies to optimized GETs, created via
lnet_create_reply_msg(), are only ever committed for rx. As such,
their msg_txni and msg_txpeer fields are NULL. lnet_incr_hstats()
does not account for this situation, so when passed one of these
messages attempts to deref a NULL pointer.

HPE-bug-id: LUS-8730
Signed-off-by: Chris Horn <hornc@cray.com>
Change-Id: I36b7c46a2d439c5e62f17df64a4f9da8f01090aa
Reviewed-on: https://review.whamcloud.com/38237
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Amir Shehata <ashehata@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>