Input: tsc2005 - add DT support

This adds DT support to the tsc2005 touchscreen driver. It also adds
regulator support to the driver if booted via DT.

Reviewed-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>