staging:iio:imu:adis16400 cleanups

a) remove irq is gpio requirement - No reason this needs to be true.
b) use actual part name in info message rather than adis16400 in all cases.
c) scrap use of IIO_CHAN to simplify move out of staging.
Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Acked-by: Michael Hennerich <Michael.Hennerich@analog.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/imu/adis16400_trigger.c

@@ -29,7 +29,7 @@ int adis16400_probe_trigger(struct iio_dev *indio_dev)
 	struct adis16400_state *st = iio_priv(indio_dev);
 
 	st->trig = iio_allocate_trigger("%s-dev%d",
-					spi_get_device_id(st->us)->name,
+					indio_dev->name,
 					indio_dev->id);
 	if (st->trig == NULL) {
 		ret = -ENOMEM;