clustermesh: Fix comments on scope of rc.mutex
clustermesh: Fix comments on scope of rc.mutex

Reported-by: da39a3ee5e6b4b0d3255bfef95601890afd80709@sayboras
Signed-off-by: Thomas Graf <5f50a84c1fa3bcff146405017f36aec1a10a9e38@cilium.io>

michi-covalent/cilium,cilium/cilium,tgraf/cilium,cilium-team/cilium,michi-covalent/cilium,tgraf/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium,tgraf/cilium,cilium/cilium,tklauser/cilium,cilium-team/cilium,tklauser/cilium,michi-covalent/cilium,tklauser/cilium,tgraf/cilium,tgraf/cilium,tklauser/cilium,michi-covalent/cilium,tgraf/cilium,tklauser/cilium,cilium/cilium