MdePkg/BaseLib: Change a variable type in a bitwise operation
    
    Change the type of variable Chr from CHAR8 to UINT32 in a
    bitwise operation, to make the two variables in the operation
    have the same size.
    https://bugzilla.tianocore.org/show_bug.cgi?id=1527
    
    Cc: Michael D Kinney <michael.d.kinney@intel.com>
    Cc: Liming Gao <liming.gao@intel.com>
    Contributed-under: TianoCore Contribution Agreement 1.1
    Signed-off-by: Shenglei Zhang <shenglei.zhang@intel.com>
    Reviewed-by: Liming Gao <liming.gao@intel.com>