Fix Python2 compat in new SDR cache code

Python2 bytes type cannot be compared to number.
Coerce into a bytearray to have python2 treat
them as numbers.

Change-Id: I8522b1eb74f4b7aebfa6a0fa68107a0df947c7f6

pyghmi/ipmi/sdr.py

@@ -841,6 +841,8 @@ class SDR(object):
                         False, self.mfg_id, self.prod_id)
 
     def add_sdr(self, sdrbytes):
+        if not isinstance(sdrbytes[0], int):
+            sdrbytes = bytearray(sdrbytes)
         newent = self.make_sdr_entry(sdrbytes)
         if newent.sdrtype == TYPE_SENSOR:
             id = '{0}.{1}.{2}'.format(