LU-1588 lnet: deadlock while shutting down router

LU-1588 lnet: deadlock while shutting down router

Should release lock on exiting of lnet_prune_rc_data(), otherwise
we will get deadlock on later attempting on lnet_net_lock().
Also, there is a wrong condition check in lnet_prune_rc_data()
can prevent router checker from shutting down.

Signed-off-by: Liang Zhen <liang@whamcloud.com>
Change-Id: I5292075453e61f300384043e2346df714c530303
Reviewed-on: http://review.whamcloud.com/3250
Tested-by: Hudson
Reviewed-by: Bobi Jam <bobijam@whamcloud.com>
Reviewed-by: Doug Oucharek <doug@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>