Raphaelcoeffic/fix sd manager (#6783)

* do not invalidate filenames buffer on EVT_REFRESH

otherwise the filenames are reset to the end of list, whereby the indexes stay the same on [LONG ENTER] (pop-up menu).

* fix vertical offset when leaving text viewer

radio/src/gui/480x272/radio_sdmanager.cpp

@@ -194,7 +194,6 @@ bool menuRadioSdManager(event_t _event)
       // no break;
 
     case EVT_ENTRY_UP:
-    case EVT_REFRESH:
       REFRESH_FILES();
       break;
 

radio/src/gui/480x272/view_text.cpp

@@ -50,6 +50,7 @@ bool menuTextView(event_t event)
       break;
 
     case EVT_KEY_FIRST(KEY_EXIT):
+      menuVerticalOffset = 0;
       popMenu();
       break;
   }