staging:iio:cdc:ad7150: Drop noisy print in probe

Also
* drop i2c_set_client_data() as now unused.
* white space cleanups

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Barry Song <song.bao.hua@hisilicon.com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210314181511.531414-9-jic23@kernel.org