iio:ad7476: Add support for ad7273/ad7274/ad7276/ad7277/ad7278

The ad7276/ad7277/ad7278 are similar to the ad7476/ad7477/ad7478 but have the
same number of leading zeros as the ad7940. The ad7273/ad7274 have a extra pin
for VREF where as for the ad7276/ad7277/ad7278 VREF is taken from VDD, but
otherwise they are compatible to the ad7276/ad7277.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index e2e6963..03791a6 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -36,9 +36,9 @@
 	select IIO_BUFFER
 	select IIO_TRIGGERED_BUFFER
 	help
-	  Say yes here to build support for Analog Devices AD7475, AD7476, AD7477,
-	  AD7478, AD7466, AD7467, AD7468, AD7495, AD7910, AD7920, AD7920 SPI analog
-	  to digital converters (ADC).
+	  Say yes here to build support for Analog Devices AD7273, AD7274, AD7276,
+	  AD7277, AD7278, AD7475, AD7476, AD7477, AD7478, AD7466, AD7467, AD7468,
+	  AD7495, AD7910, AD7920, AD7920 SPI analog to digital converters (ADC).
 
 	  If unsure, say N (but it's safe to say "Y").