iio: hid-sensor-prox: Introduce PM

Use common hid sensor iio pm functions. Also the poll time read and
wait is part of power up function of hid sensor iio pm function, so
remove from the client drivers.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>