iio: xilinx-xadc: Remove code to set trigger parent

iio: xilinx-xadc: Remove code to set trigger parent

iio_trigger_set_drvdata() sets the trigger device parent to first
argument of viio_trigger_alloc(), no need to do it again in the driver
code.

In xadc_alloc_trigger, given dev is indio_dev->dev.parent, and we call
devm_iio_trigger_alloc wit dev as argument,  we do not have to set
data->trig->dev.parent to indio_dev->dev.parent anymore.

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210309193620.2176163-9-gwendal@chromium.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>