sync.ModbusUdpClient: Correct reference to settimeout.

I could not find a 'settimeout' (case-insensitive) anywhere in the
codebase other than on this line, but I *did* see it was a method of
socket.socket.

So I'll assume that this was *supposed* to be calling
socket.socket.settimeout.

pymodbus/client/sync.py

@@ -228,7 +228,7 @@ def connect(self):
         try:
             family = ModbusUdpClient._get_address_family(self.host)
             self.socket = socket.socket(family, socket.SOCK_DGRAM)
-            self.settimeout(self.timeout)
+            self.socket.settimeout(self.timeout)
         except socket.error, ex:
             _logger.error('Unable to create udp socket %s' % ex)
             self.close()