input: ft5x06_ts: add support for pinctrl framework

Migrate the Focaltech driver to use pinctrl framework for GPIO
configuration so that driver is compatible with targets that
use and targets that don't use pinctrl framework.

Change-Id: I84fc2a6d30f831b4b054780b107ce105614855ea
Signed-off-by: Mao Li <maol@codeaurora.org>