drivers/sensor: lsm6dso: Disable sensor hub before reset

Per an ST app note, the sensor hub I2C controller should be disabled
before doing a software reset.  Possibly, this is because the sensor hub
could be in the middle of the an I2C transaction to a sensor when it is
reset.  Disabling it and then waiting makes sure it has quiesced before
resetting.

Signed-off-by: Trent Piepho <trent.piepho@igorinstitute.com>