Input: add a new driver for GPIO beeper

This patch adds a new driver for the beeper controlled via GPIO pin.
The driver does not depend on the architecture and is positioned as
a replacement for the specific drivers that are used for this function.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>