BaseTools: Fix the build report issue about Structure PCD
    
    https://bugzilla.tianocore.org/show_bug.cgi?id=1472
    build report use incorrect method to parse DynamicDefault/DynamicExDefault
    and DynamicVpd/DynamicExVpd structure Pcd value.
    
    This patch is to fix this issue.
    
    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>