LU-6142 lnet: convert kiblnd/ksocknal_thread_start to vararg

LU-6142 lnet: convert kiblnd/ksocknal_thread_start to vararg

Rather than requiring the called to format a thread name into a temp
buffer, change these thread_start function to accept a format and
args, and to hand them directly to kthread_run().

This is done with a macro rather than a function as the functions are
trivial and varargs is slightly easier with macros.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I73926ef38a9e84061d1a3f9acf5c0be4a247f957
Reviewed-on: https://review.whamcloud.com/44122
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>