BaseTools: Fixed the build fail issue for cases

https://bugzilla.tianocore.org/show_bug.cgi?id=1386
This patch is going to fix the regression issue that is
introduced by commit 72a1d77694

The issue will happen in the following cases:
1. There is no Pcd value assignment in Dsc file
2. There are duplicate Pcd filed assignment

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>

BaseTools/Source/Python/Workspace/MetaFileParser.py

@@ -1203,7 +1203,7 @@ class DscParser(MetaFileParser):
                 return
         TokenList = GetSplitValueList(self._CurrentLine, TAB_VALUE_SPLIT, 1)
         self._CurrentPcdName = TokenList[0]
-        if TokenList[1].strip().startswith("{CODE"):
+        if len(TokenList) == 2 and TokenList[1].strip().startswith("{CODE"):
             self._PcdDataTypeCODE = True
             self._PcdCodeValue = TokenList[1].strip()