hle: Add proper type for result code

This should clean up all HLE errorcode in the codebase.

I didn't removed Rust::Result as this should be a cleanup for another
iteration.

include/services/am.hpp

@@ -3,6 +3,7 @@
 #include "kernel_types.hpp"
 #include "logger.hpp"
 #include "memory.hpp"
+#include "result/result.hpp"
 
 class AMService {
 	Handle handle = KernelHandles::AM;