Kernel: Migrate ARP table locking to ProtectedValue

Author: https://github.com/boricj
Commit: 738e604bfc
Pull-request: https://github.com/SerenityOS/serenity/pull/8851
Reviewed-by: https://github.com/awesomekling ✅
Reviewed-by: https://github.com/bgianfo

Kernel/Net/Routing.h

@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <Kernel/Locking/Lockable.h>
+#include <Kernel/Locking/ProtectedValue.h>
 #include <Kernel/Net/NetworkAdapter.h>
 #include <Kernel/Thread.h>
 
@@ -27,6 +27,6 @@ enum class UpdateArp {
 void update_arp_table(const IPv4Address&, const MACAddress&, UpdateArp update);
 RoutingDecision route_to(const IPv4Address& target, const IPv4Address& source, const RefPtr<NetworkAdapter> through = nullptr);
 
-Lockable<HashMap<IPv4Address, MACAddress>>& arp_table();
+ProtectedValue<HashMap<IPv4Address, MACAddress>>& arp_table();
 
 }