iio: adis16400: Add ADIS16445 support

The ADIS16445 is similar to the ADIS16448, but without the magnetometer and
pressure channels as well as different scale factors for the gyroscope and
accelerometer outputs.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>