gst/interfaces.*: Apply patch from Zaheer Abbas Merali to implement this method. Not that it's not .list_channels() d...

Original commit message from CVS:
* gst/interfaces.defs:
* gst/interfaces.override (_wrap_gst_color_balance_list_channels):
Apply patch from Zaheer Abbas Merali to implement this method. Not
that it's not .list_channels() due to conflict with a method of
the same name in the GstTuner interface