Input: cyapa - add runtime power management support

This change implements runtime PM support in the driver and adds
runtime_suspend_scanrate_ms power management interface in device's power
group, so users or applications can control the runtime power management
strategy of trackpad device according to their requirements.

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