BaseTools: Remove equality operator with None

replace "== None" with "is None" and "!= None" with "is not None"

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

BaseTools/Scripts/PackageDocumentTools/plugins/EdkPlugins/edk2/model/dec.py

@@ -77,7 +77,7 @@ class DECSection(ini.BaseINISection):
         return arr[1]
 
     def IsArchMatch(self, arch):
-        if arch == None or self.GetArch() == 'common':
+        if arch is None or self.GetArch() == 'common':
             return True
 
         if self.GetArch().lower() != arch.lower():