Input: bu21013_ts - add support for Device Tree booting

Now we can register the BU21013_ts touch screen when booting with Device
Tree enabled. Here we parse all the necessary components previously
expected to be passed from platform data.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>