Fixed pcan Unpack error (#1767)

* Fixed pcan Unpack error

PCANBasic.GetValue() must always return a Tuple with 2 elements, otherwise PcanBus._detect_available_configs() raises a "not enough values to unpack" error at line 718.

* Fixed typo

Author: FedericoSpada

can/interfaces/pcan/basic.py

@@ -967,7 +967,7 @@ def GetValue(self, Channel, Parameter):
             elif Parameter == PCAN_ATTACHED_CHANNELS:
                 res = self.GetValue(Channel, PCAN_ATTACHED_CHANNELS_COUNT)
                 if TPCANStatus(res[0]) != PCAN_ERROR_OK:
-                    return (TPCANStatus(res[0]),)
+                    return TPCANStatus(res[0]), ()
                 mybuffer = (TPCANChannelInformation * res[1])()
 
             elif (