messagelistview: fix message loading

On some cases (like many edition/reply) the atYBeginning is still true
causing the view to not load messages anymore (after retrying it loads
as the beginning)

Change-Id: I9da474224f6fc0a39cf405c8bfe9d5201849ea64

src/app/mainview/components/MessageListView.qml

@@ -297,7 +297,7 @@ JamiListView {
         }
 
         function onMoreMessagesLoaded() {
-            if (root.contentHeight < root.height) {
+            if (root.contentHeight < root.height || root.atYBeginning) {
                 root.loadMoreMsgsIfNeeded()
             }
         }