Input: bu21013_ts - remove support for platform data

There are no current users of the platform data in the tree, and
any new users should either use device tree, or static device
properties to describe the device.

This change drop the platform data definition and handling and moves the
driver over to generic device properties API. We also drop support for the
external clock. If it is needed we will have to extend the bindings to
supply the clock reference and handle it properly in the driver.

Also, wakeup setting should be coming from I2C client.

Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>