Input: cyapa - add regulator vcc support

We need to power up the chip before we can initialize it.

On systems that delegate task of powering up regulators to firmware we
assume that we'll be simply given a dummy regulator.

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