Lock-order inversion between sysctl_rman and rman_fini creates ABBA deadlock potential (rman_fini dead code)

Summary

sysctl_rman acquires rman_tok (:669) then rm_slock (:698). rman_fini acquires rm_slock (:162) then rman_tok (:174) = ABBA inversion. rm_hold cannot help deadlock occurs before fini reaches rm_hold check. rman_fini has NO in-tree caller (dead code) so not currently exploitable. sysctl hw.bus.rman unprivileged CTLFLAG_RD. Would deadlock if module calls rman_fini during detach while user reads sysctl. Fix: consistent lock order acquire rman_tok before rm_slock in fini.