BaseTools: Add MaxSizeUserSet to Pcd deepcopy function
    
    MaxSizeUserSet is missing in Pcd deepcopy function.
    This patch is to add it back to Pcd deepcopy function.
    
    Contributed-under: TianoCore Contribution Agreement 1.1
    Signed-off-by: Bob Feng <bob.c.feng@intel.com>
    Cc: Liming Gao <liming.gao@intel.com>
    Reviewed-by: Liming Gao <liming.gao@intel.com>