Input: cyapa - add sysfs interfaces support in the cyapa driver

Introduce control interfaces that are commonly used in pre- and after
production, for trackpad device state checking, managing and firmware image
updating.  These interfaces include mode, firmware_version and product_id
interfaces for reading firmware version and trackpad device product id
values, and update_fw interface to command firmware image update process.
There are also baseline and calibrate interfaces for reading and checking
trackpad device's sensors states.

Signed-off-by: Dudley Du <dudl@cypress.com>
Tested-by: Jeremiah Mahler <jmmahler@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>