atmel maxtouch: allow selection of I2C address

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
nitrogen6x: use configurable I2C address for Atmel MaxTouch touch screen

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
atmel maxtouch: allow calibration parameter

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>