Input: sun4i-ts - add support for touchpanel controller on A31

The Allwinner A31 SoC (sun6i) has the same resistive touchpanel controller
as on other sunxi platforms. The only difference between the variants is
the control bits for enabling operations are left-shifted by 1 on the A31.

Also update the comment for the original temperature sensor with
information from Allwinner.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>