Scheduler: Remove arm_interface lock and a few corrections.

src/core/arm/arm_interface.h

@@ -6,7 +6,6 @@
 
 #include <array>
 #include <vector>
-#include <mutex>
 #include "common/common_types.h"
 
 namespace Common {
@@ -165,14 +164,6 @@ public:
         std::string name;
     };
 
-    void Lock() {
-        guard.lock();
-    }
-
-    void Unlock() {
-        guard.unlock();
-    }
-
     std::vector<BacktraceEntry> GetBacktrace() const;
 
     /// fp (= r29) points to the last frame record.
@@ -187,7 +178,6 @@ protected:
     /// System context that this ARM interface is running under.
     System& system;
     CPUInterruptHandler& interrupt_handler;
-    std::mutex guard;
 };
 
 } // namespace Core