iio: sx9360: fix iio event generation

To convert SX9360 status register ["REG_STAT"], into a channel
index, we need to right shift by |stat_offset|, not left shift.
Also the PROXSTAT bit (3) is for channel 1 (PHM, Phase Measured), not (PHR,
Phase Reference, channel 0), so the offset is 2 instead of 3.

Fixes: 1cdb4c47 ("iio:proximity:sx9360: Add sx9360 support")
Signed-off-by: Jongpil Jung <jongpil19.jung@samsung.com>
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Link: https://lore.kernel.org/r/20220122213444.745152-1-gwendal@chromium.org


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