staging: iio: adc: Enable driver support for ad7887 AD converter

Enable support for AD7887:  SPI Micropower, 2-Channel, 125 kSPS, 12-Bit ADC

staging: iio: adc: Fix according to review feedback

Review feedback by Jonathan Cameron:
	Combine statements.
	Document struct members.
	Remove redundant variable initialization.
	Simplify multichannel scan from ring logic.
	Fix coding style.

[v2]
staging: iio: adc: ad7887: Fix typos

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/staging/iio/adc/Makefile b/drivers/staging/iio/adc/Makefile
index a7dce6b..6f231a2 100644
--- a/drivers/staging/iio/adc/Makefile
+++ b/drivers/staging/iio/adc/Makefile
@@ -15,6 +15,10 @@
 ad7476-$(CONFIG_IIO_RING_BUFFER) += ad7476_ring.o
 obj-$(CONFIG_AD7476) += ad7476.o
 
+ad7887-y := ad7887_core.o
+ad7887-$(CONFIG_IIO_RING_BUFFER) += ad7887_ring.o
+obj-$(CONFIG_AD7887) += ad7887.o
+
 obj-$(CONFIG_AD7150) += ad7150.o
 obj-$(CONFIG_AD7152) += ad7152.o
 obj-$(CONFIG_AD7291) += ad7291.o