kernel: Remove unnecessary includes

Over the course of the changes to the kernel code, a few includes are no
longer necessary, particularly with the change over to std::shared_ptr
from Boost's intrusive_ptr.

src/core/hle/kernel/resource_limit.h

@@ -5,6 +5,8 @@
 #pragma once
 
 #include <array>
+#include <memory>
+
 #include "common/common_types.h"
 #include "core/hle/kernel/object.h"