devices: Use list_add_tail() instead of list_add() to register a device

This patch fixes a problem spotted on Glacier/Canyonlands (and most
likely lots of other board ports), that no serial output was seen
after console initialization in console_init_r(). This is because the
last added console device was used instead of the first added.

This patch fixes this problem by using list_add_tail() instead of
list_add() to register a device. This way the first added console
is used again.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/common/devices.c b/common/devices.c
index 8beebe2..7d0ac2e 100644
--- a/common/devices.c
+++ b/common/devices.c
@@ -155,7 +155,7 @@
 	_dev = device_clone(dev);
 	if(!_dev)
 		return -1;
-	list_add(&(_dev->list), &(devs.list));
+	list_add_tail(&(_dev->list), &(devs.list));
 	return 0;
 }