IIO: GYRO: ADXRS450: Don't issue two messages, use two transfers

Don't issue the same message twice, use two transfers and group them together

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>