staging: iio: isl29028: remove unnecessary error logging in isl29028_chip_init_and_power_on()

If the call to isl29028_chip_init_and_power_on() in isl29028_probe()
fails, then isl29028_probe() will log an error message. All of the
error paths in that call path already have error logging in place. This
patch removes the unnecessary logging.

Signed-off-by: Brian Masney <masneyb@onstation.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>