LU-12635 lnet: Fix style issues for module.c conctl.c

LU-12635 lnet: Fix style issues for module.c conctl.c

This patch fixes issues reported by checkpatch for the file
selftest/module.c and selftest/conctl.c.
Linux 5.3 enforces the use of 'fallthrough' which is also
suggested by checkpatch

Test-Parameters: trivial
Cray-bug-id: LUS-7690
Signed-off-by: Shaun Tancheff <stancheff@cray.com>
Change-Id: If650375f63f27c01c40e251059fa242f919854be
Reviewed-on: https://review.whamcloud.com/35802
Reviewed-by: Petros Koutoupis <pkoutoupis@cray.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Arshad Hussain <arshad.super@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>