LU-10391 lnet: set msg field for lnet message header

LU-10391 lnet: set msg field for lnet message header

During testing messages sent for larger NID setups was missing
the actual message. Fill in the header msg field to properly
send the total message.

Test-Parameters: trivial testlist=sanity-lnet
Test-Parameters: serverversion=2.12 serverdistro=el7.9 testlist=runtests
Test-Parameters: clientversion=2.12 testlist=runtests
Fixes: 7b31ef0bbac ("LU-10391 socklnd: add hello message version 4")
Change-Id: I36ef48a239a64a9002f8dc2683437bc3c57492e6
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50716
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Frank Sehr <fsehr@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>