pkg/bpf: remove unused (Get|Set)MapPrefix funcs
pkg/bpf: remove unused (Get|Set)MapPrefix funcs

Also unexport SetMapRoot since it's not used outside the package.

Signed-off-by: Tobias Klauser <9249c549618448e4c699e8032ba6c7f0d7fd4b7f@distanz.ch>

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