core: device_memory: Use memory size reported by KSystemControl.

- That way, we can consolidate the memory layout to one place.

src/core/device_memory.cpp

@@ -3,10 +3,13 @@
 // Refer to the license.txt file included.
 
 #include "core/device_memory.h"
+#include "hle/kernel/board/nintendo/nx/k_system_control.h"
 
 namespace Core {
 
-DeviceMemory::DeviceMemory() : buffer{DramMemoryMap::Size, 1ULL << 39} {}
+DeviceMemory::DeviceMemory()
+    : buffer{Kernel::Board::Nintendo::Nx::KSystemControl::Init::GetIntendedMemorySize(),
+             1ULL << 39} {}
 DeviceMemory::~DeviceMemory() = default;
 
 } // namespace Core