staging:iio:ad7606: Re-add missing scale attribute

Commit 50ac23be ("staging:iio:adc:ad7606 add local define for chan_spec
structures.") accidentally removed the scale info_mask flag. This patch
adds it back again.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: stable <stable@vger.kernel.org>  [3.2+]
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/iio/adc/ad7606_core.c

@@ -235,7 +235,8 @@ static const struct attribute_group ad7606_attribute_group_range = {
 		.indexed = 1,					\
 		.channel = num,					\
 		.address = num,					\
-		.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT,	\
+		.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |	\
+				IIO_CHAN_INFO_SCALE_SHARED_BIT, \
 		.scan_index = num,				\
 		.scan_type = IIO_ST('s', 16, 16, 0),		\
 	}