LU-6142 lnet: Fix style issues for rpc.h

LU-6142 lnet: Fix style issues for rpc.h

This patch fixes issues reported by checkpatch
for file lnet/selftest/rpc.h

Test-Parameters: trivial testlist=sanity-lnet
Signed-off-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Change-Id: I99524bd815936c95d048a7617acfde3327d8d5e1
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/55732
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>