EmulatorPkg: don't display the cpu current speed
    
    REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1686
    
    The bug reporter wish to display nothing as the CPU is virtual
    
    Reviewed-by: Ray Ni <ray.ni@intel.com>
    Cc: Jordan Justen <jordan.l.justen@intel.com>
    Cc: Andrew Fish <afish@apple.com>
    Cc: Ray Ni <ray.ni@intel.com>
    Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>