LU-9679 lnet: always check return of try_module_get()

LU-9679 lnet: always check return of try_module_get()

try_module_get() can fail, so the return value should be checked.
If we *know* that we already hold a reference, __module_get()
should be used instead.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Id526f9ae3829a50fe7df7069230804322cd4558e
Reviewed-on: https://review.whamcloud.com/36854
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Chris Horn <hornc@cray.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>