Input: gpio_mouse - convert to use GPIO descriptors

This converts the GPIO mouse to use descriptors and fwnode properties. The
polarity settings go out the window since GPIO descriptor already know
about polarity so this should be configured in device tree or ACPI or
similar.

Set scanning interval by default to 50ms if not found as a property on the
device.

Acked-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>