PictureFlow: Remove menu items for "Return" and "Clear Playlist"

On all players, it should be possible to return from the Main Menu
by pressing the Back or Menu key. Unless I'm missing something...

"Clear Playlist" has hopefully become superfluous after the "Playing Next"
context menu was added, which offers similar functionality.

Change-Id: I741544978fb7936b8d5a34dfc656472e20c1737e

apps/lang/english.lang

@@ -15110,16 +15110,16 @@
 </phrase>
 <phrase>
   id: LANG_CLEAR_PLAYLIST
-  desc: in the pictureflow main menu
+  desc: deprecated
   user: core
   <source>
-    *: "Clear playlist"
+    *: ""
   </source>
   <dest>
-    *: "Clear playlist"
+    *: ""
   </dest>
   <voice>
-    *: "Clear playlist"
+    *: ""
   </voice>
 </phrase>
 <phrase>