src/locktest.c: Clean up client command passing

src/locktest.c: Clean up client command passing

The client was using the test index rather than the values being passed
to it for a command.  While this technically worked it is cleaner to
fully initialize the command message and use the values in that message.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>