BaseTools:change some incorrect parameter defaults

BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=1858

for Dict={},There are pitfalls in the way this default parameter is set
and Dict is not used in functions, other functions have these two cases,
I will change some incorrect parameter defaults

This patch is going to fix this issue

Cc: Liming Gao <liming.gao@intel.com>
Cc: Bob Feng <bob.c.feng@intel.com>
Signed-off-by: Zhiju.Fan <zhijux.fan@intel.com>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>

BaseTools/Source/Python/GenFds/FvImageSection.py

@@ -47,9 +47,11 @@ class FvImageSection(FvImageSectionClassObject):
     #   @param  Dict        dictionary contains macro and its value
     #   @retval tuple       (Generated file name, section alignment)
     #
-    def GenSection(self, OutputPath, ModuleName, SecNum, KeyStringList, FfsInf = None, Dict = {}, IsMakefile = False):
+    def GenSection(self, OutputPath, ModuleName, SecNum, KeyStringList, FfsInf = None, Dict = None, IsMakefile = False):
 
         OutputFileList = []
+        if Dict is None:
+            Dict = {}
         if self.FvFileType is not None:
             FileList, IsSect = Section.Section.GetFileList(FfsInf, self.FvFileType, self.FvFileExtension)
             if IsSect :