ARM: AT91: IIO: Add AT91 ADC driver.

Add the ADC driver for Atmel's AT91SAM9G20-EK, AT91SAM9M10G45-EK
and AT91SAM9X5 family boards.

It has support for both software and hardware triggers.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 5552491..e425afd 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -9,4 +9,5 @@
 
 obj-$(CONFIG_IIO_KFIFO_BUF) += kfifo_buf.o
 
+obj-y += adc/
 obj-y += amplifiers/