Refresh page after updating partition sizes

Some (all?) devices do not update the partition size displayed on the
backup screen when selecting "Refresh Sizes". Refresh the page after
recalculating sizes.

Change-Id: Id34da6c738f86501f73cbd7874f6921d1cda32c4
diff --git a/gui/devices/1920x1200/res/ui.xml b/gui/devices/1920x1200/res/ui.xml
index 251c5fb..f126572 100644
--- a/gui/devices/1920x1200/res/ui.xml
+++ b/gui/devices/1920x1200/res/ui.xml
@@ -1639,7 +1639,10 @@
 				<font resource="font" color="%button_text_color%" />
 				<text>Refresh Sizes</text>
 				<image resource="main_button" />
-				<action function="refreshsizes"></action>
+				<actions>
+					<action function="refreshsizes"></action>
+					<action function="page">backup</action>
+				</actions>
 			</object>
 
 			<object type="button">