LU-10467 ldlm: convert l_wait_event in __ldlm_namespace_free

LU-10467 ldlm: convert l_wait_event in  __ldlm_namespace_free

The l_wait_event call in __ldlm_namespace_free() can do one
of two things depending on which LWI_* setup call is in effect.
If 'force', it ignores signals and times out after 1/4 second.
If '!force', it has no timeout but allows fatal signals.

So change it to two separate calls: wait_event_idle_timeout()
or l_wait_event_abortable().

Signed-off-by: Mr NeilBrown <neilb@suse.com>
Change-Id: I1ac7ff5daa80581010cd913f01650c07ac40c151
Reviewed-on: https://review.whamcloud.com/35989
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Shaun Tancheff <stancheff@cray.com>
Reviewed-by: Petros Koutoupis <pkoutoupis@cray.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>