staging:iio: Move adis library out of staging

Now that the adis library no longer depends on the sw_ring buffer implementation
we can move it out of staging.

While we are at it also sort the entries in the iio Kconfig and Makefile to be
in alphabetical order.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/imu/Kconfig b/drivers/iio/imu/Kconfig
new file mode 100644
index 0000000..c24410c
--- /dev/null
+++ b/drivers/iio/imu/Kconfig
@@ -0,0 +1,11 @@
+config IIO_ADIS_LIB
+	tristate
+	help
+	  A set of IO helper functions for the Analog Devices ADIS* device family.
+
+config IIO_ADIS_LIB_BUFFER
+	bool
+	select IIO_TRIGGERED_BUFFER
+	help
+	  A set of buffer helper functions for the Analog Devices ADIS* device
+	  family.