IIO: Move the core files to drivers/iio

Take the core support + the kfifo buffer implentation out of
staging.  Whilst we are far from done in improving this subsystem
it is now at a stage where the userspae interfaces (provided by
the core) can be considered stable.

Drivers will follow over a longer time scale.

Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/Makefile b/drivers/Makefile
index 95952c8..cdbe362 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -134,3 +134,4 @@
 obj-$(CONFIG_HYPERV)		+= hv/
 
 obj-$(CONFIG_PM_DEVFREQ)	+= devfreq/
+obj-$(CONFIG_IIO)		+= iio/