iio: add support of the max1027

This driver add partial support of the
maxim 1027/1029/1031. Differential mode is not
supported.

It was tested on armadeus apf27 board.

Signed-off-by: Philippe Reynes <tremyfr@yahoo.fr>
Reviewed-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index ee9d85e..de6d2f4 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -131,6 +131,15 @@
 	help
 	  Say yes here to build support for TI LP8788 ADC.
 
+config MAX1027
+	tristate "Maxim max1027 ADC driver"
+	depends on SPI
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for Maxim SPI ADC models
+	  max1027, max1029 and max1031.
+
 config MAX1363
 	tristate "Maxim max1363 ADC driver"
 	depends on I2C