staging:iio: one more fix for IIO_RING_BUFFER not enabled.

Same problem as seen and fixed in adis16204 et al.
These were fixed by Randy in:
staging: fix more iio builds when IIO_RING_BUFFER is not enabled

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/accel/adis16240.h

@@ -141,7 +141,6 @@ struct adis16240_state {
 
 int adis16240_set_irq(struct iio_dev *indio_dev, bool enable);
 
-#ifdef CONFIG_IIO_RING_BUFFER
 /* At the moment triggers are only used for ring buffer
  * filling. This may change!
  */
@@ -153,6 +152,7 @@ int adis16240_set_irq(struct iio_dev *indio_dev, bool enable);
 #define ADIS16240_SCAN_AUX_ADC	4
 #define ADIS16240_SCAN_TEMP	5
 
+#ifdef CONFIG_IIO_RING_BUFFER
 void adis16240_remove_trigger(struct iio_dev *indio_dev);
 int adis16240_probe_trigger(struct iio_dev *indio_dev);