kern: implement CallSecureMonitor, some of GetInfo/GetSystemInfo

libraries/libmesosphere/include/mesosphere/board/nintendo/nx/kern_k_system_control.hpp

@@ -63,6 +63,9 @@ namespace ams::kern::board::nintendo::nx {
             /* Power management. */
             static void SleepSystem();
             static NORETURN void StopSystem();
+
+            /* User access. */
+            static void CallSecureMonitorFromUser(ams::svc::lp64::SecureMonitorArguments *args);
     };
 
 }