cilium: swap RegisterChannel with SetupSignalListener
cilium: swap RegisterChannel with SetupSignalListener

The test and assignment of channels to the channel array is lockless,
lets be on safe side and register all channels first before doing the
signal.SetupSignalListener().

Suggested-by: Martynas Pumputis <6b0d31c0d563223024da45691584643ac78c96e8@lambda.lt>
Signed-off-by: Daniel Borkmann <3d0f3b9ddcacec30c4008c5e030e6c13a478cb4f@iogearbox.net>

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