iio: of_iio_channel_get_by_name() returns non-null pointers for error legs

Currently in the inkern.c code for IIO framework, the function
of_iio_channel_get_by_name() will return a non-NULL pointer when
it cannot find a channel using of_iio_channel_get() and when it
tries to search for 'io-channel-ranges' property and fails. This
is incorrect behaviour as the function which calls this expects
a NULL pointer for failure. This patch rectifies the issue.
Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Cc: Stable@vger.kernel.org

drivers/iio/inkern.c

@@ -183,7 +183,7 @@ static struct iio_channel *of_iio_channel_get_by_name(struct device_node *np,
 		else if (name && index >= 0) {
 			pr_err("ERROR: could not get IIO channel %s:%s(%i)\n",
 				np->full_name, name ? name : "", index);
-			return chan;
+			return NULL;
 		}
 
 		/*
@@ -193,8 +193,9 @@ static struct iio_channel *of_iio_channel_get_by_name(struct device_node *np,
 		 */
 		np = np->parent;
 		if (np && !of_get_property(np, "io-channel-ranges", NULL))
-			break;
+			return NULL;
 	}
+
 	return chan;
 }
 
@@ -317,6 +318,7 @@ struct iio_channel *iio_channel_get(struct device *dev,
 		if (channel != NULL)
 			return channel;
 	}
+
 	return iio_channel_get_sys(name, channel_name);
 }
 EXPORT_SYMBOL_GPL(iio_channel_get);