Fail set_user_priv on a rejected privilege change

Every other /data call checks the status, this one discarded the
response, so an SMM that refused the user record was reported to the
caller as a successful privilege change.

confluent_server/aiohmi/ipmi/oem/lenovo/nextscale.py

@@ -735,9 +735,11 @@ class SMMClient(object):
             username = bytes(rsp['data']).rstrip(b'\x00')
             if not isinstance(username, str):
                 username = username.decode('utf8')
-            await self.webrequest(
+            rsp, status = await self.webrequest(
                 '/data', 'set=user({0},1,{1},511,,4,15,0)'.format(
                     uid, username))
+            if status != 200:
+                raise Exception(rsp)
 
     async def reseat_bay(self, bay):
         bay = int(bay)