Kernel: remove Semaphore::is_blocked

this will not mean anything after semaphores can spuriously wake up

kernel/include/kernel/Semaphore.h

@@ -8,15 +8,6 @@ namespace Kernel
 	public:
 		void block();
 		void unblock();
-		bool is_blocked() const { return m_blocked; }
-
-	private:
-		void set_blocked(bool blocked) { m_blocked = blocked; }
-
-	private:
-		bool m_blocked { false };
-
-		friend class Scheduler;
 	};
 
 }