staging: greybus: fix get_channel_from_mode() failure path

The get_channel_from_mode() function is supposed to return the channel
which matches the mode.  But it has a bug where if it doesn't find a
matching channel then it returns the last channel.  It should return
NULL instead.

Also remove an unnecessary NULL check on "channel".

Fixes: 2870b52b ("greybus: lights: add lights implementation")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Rui Miguel Silva <rmfrfs@gmail.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/379c0cb4-39e0-4293-8a18-c7b1298e5420@moroto.mountainSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/greybus/light.c

@@ -100,15 +100,15 @@ static struct led_classdev *get_channel_cdev(struct gb_channel *channel)
 static struct gb_channel *get_channel_from_mode(struct gb_light *light,
 						u32 mode)
 {
-	struct gb_channel *channel = NULL;
+	struct gb_channel *channel;
 	int i;
 
 	for (i = 0; i < light->channels_count; i++) {
 		channel = &light->channels[i];
-		if (channel && channel->mode == mode)
-			break;
+		if (channel->mode == mode)
+			return channel;
 	}
-	return channel;
+	return NULL;
 }
 
 static int __gb_lights_flash_intensity_set(struct gb_channel *channel,