iio: imu: inv_mpu6050: add WoM suspend wakeup with low-power mode

Add wakeup from suspend for WoM when enabled and put accel in low-power
mode when suspended. Requires rewriting pwr_mgmt_1 register handling and
factorize out accel LPF settings. Use a low-power rate similar to the chip
sampling rate but always lower for a best match of the sampling rate while
saving power and adjust threshold to follow the required roc value.

Signed-off-by: Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@tdk.com>
Link: https://lore.kernel.org/r/20240311160557.437337-5-inv.git-commit@tdk.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>