input: tsc2007 - drop the driver_module assignment in iio interface.

This is now handled via some macro magic during the register.  The
field in iio_info will be removed shortly.

Cc: Linux Input <linux-input@vger.kernel.org>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>