Fix convgridone
Fix convgridone

Still was referring to "x" which doesn't exist any more.

SKA-ScienceDataProcessor/algorithm-reference-library,SKA-ScienceDataProcessor/algorithm-reference-library,SKA-ScienceDataProcessor/algorithm-reference-library,SKA-ScienceDataProcessor/algorithm-reference-library,SKA-ScienceDataProcessor/algorithm-reference-library