iio: sx9310: Support setting debounce values

iio: sx9310: Support setting debounce values

The rising and falling directions can be debounced in the hardware as
"close" and "far" debounce settings. Add support for these as rising and
falling debounce settings.

Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Cc: Daniel Campello <campello@chromium.org>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Gwendal Grignou <gwendal@chromium.org>
Cc: Evan Green <evgreen@chromium.org>
Link: https://lore.kernel.org/r/20201007011735.1346994-5-swboyd@chromium.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>