iio: accel: adis16209: remove unneeded spi_set_drvdata()

There is no matching spi_get_drvdata() in the driver. This looks like a
left-over from before the driver was converted to device-managed functions.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20201119141806.84827-1-alexandru.ardelean@analog.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>