dt-bindings: iio: imu: mpu6050: Add level shifter

Add a level shifter flag as found in ancient platform data struct:
level_shifter: 0: VLogic, 1: VDD

Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@tdk.com>
Link: https://lore.kernel.org/r/20230927173245.2151083-2-andreas@kemnade.info


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