recovery: Move sideload (non)cancellation to its own key

 * We use KEY_REFRESH for actually refreshing menus, which is
   useful when handling hotpluggable storage.
   We don't want that to interact with the sideload menu.

Change-Id: Id7f5c06385e613648b3f727fc5e91eb3206406cf
diff --git a/recovery_ui/device.cpp b/recovery_ui/device.cpp
index 9c5de24..d006cca 100644
--- a/recovery_ui/device.cpp
+++ b/recovery_ui/device.cpp
@@ -157,6 +157,9 @@
     case KEY_REFRESH:
       return kRefresh;
 
+    case KEY_AGAIN:
+      return kDoSideload;
+
     default:
       // If you have all of the above buttons, any other buttons
       // are ignored. Otherwise, any button cycles the highlight.