Input: WM97xx - add chip driver for WM9712 touchscreen

Signed-off-by: Liam Girdwood <liam.girdwood@wolfsonmicro.com>
Signed-off-by: Graeme Gregory <gg@opensource.wolfsonmicro.com>
Signed-off-by: Mike Arthur <mike.arthur@wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Lars Munch <lars@segv.dk>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>