BaseTools: Fix the bug to handle the read-only file

change the 'r+b' to 'rb' for some file's open, since these files we only
read it and no need to write. It can fix the bug that the file's attribute
had been set to read-only.

Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Yonghong Zhu <yonghong.zhu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

BaseTools/Source/Python/GenFds/FfsFileStatement.py

@@ -101,7 +101,7 @@ class FileStatement (FileStatementClassObject) :
                     MaxAlignValue = 1
                     for Index, File in enumerate(self.FileName):
                         try:
-                            f = open(File, 'r+b')
+                            f = open(File, 'rb')
                         except:
                             GenFdsGlobalVariable.ErrorLogger("Error opening RAW file %s." % (File))
                         Content = f.read()