Modify mb manager initializing implementation.

    1. Use macros to point to submit/flush functions for different uarch,
       instead of using function pointers.
    2. Move reset_ooo_mgr to mb_mgr_code_aarch64.h, to reduce duplicate
       code.

Change-Id: I9d95cce82274d7da111c35d63fe5ee2b1485922d