[Kernel] Use tables for export groups.

src/xenia/kernel/xboxkrnl/xboxkrnl_io.cc

@@ -735,9 +735,8 @@ dword_result_t IoCreateDevice_entry(dword_t device_struct, dword_t r4,
 }
 DECLARE_XBOXKRNL_EXPORT1(IoCreateDevice, kFileSystem, kStub);
 
-void RegisterIoExports(xe::cpu::ExportResolver* export_resolver,
-                       KernelState* kernel_state) {}
-
 }  // namespace xboxkrnl
 }  // namespace kernel
 }  // namespace xe
+
+DECLARE_XBOXKRNL_EMPTY_REGISTER_EXPORTS(Io);