revlog: drop silly `raw` parameter to `rawdata` function

This is a leftover from `revision` and does not make sense for `rawdata`

mercurial/revlog.py

@@ -1677,7 +1677,7 b' class revlog(object):'
 
         return text
 
-    def rawdata(self, nodeorrev, _df=None, raw=False):
+    def rawdata(self, nodeorrev, _df=None):
         """return an uncompressed raw data of a given node or revision number.
 
         _df - an existing file handle to read from. (internal-only)