BaseTools: Clean up not used code in BuildClassObject

BaseTools: Clean up not used code in BuildClassObject

V2: Add back "from Common.DataType import *"

1. Remove some import statement that are not used.
2. Remove the Type value in the LibraryClassObject because we don't
actually use it.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Jaben Carsey <jaben.carsey@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Yonghong Zhu <yonghong.zhu@intel.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>