The MediaTek keypad can operate in two modes: single key or double key.
The driver only supports single key mode. In double key mode, the
row/column calculation based on the key is different.
Add a calc_row_col function pointer which will be different based on
single/double key mode.
No functional change.
Suggested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
Signed-off-by: Mattijs Korpershoek <mkorpershoek@xxxxxxxxxxxx>