python: Fix attempt to use a bool as a function.

A bool (has_lock) was being accessed as a function call leading to a
runtime exception.

Signed-off-by: Sumit Garg <sumit@extremenetworks.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>

python/ovs/db/idl.py

@@ -875,7 +875,7 @@ def commit(self):
             return self._status
 
         # If we need a lock but don't have it, give up quickly.
-        if self.idl.lock_name and not self.idl.has_lock():
+        if self.idl.lock_name and not self.idl.has_lock:
             self._status = Transaction.NOT_LOCKED
             self.__disassemble()
             return self._status