wear_ui: Remove backgroundIcon.

It's covered by the equivalent variable in ScreenRecoveryUI:
  GRSurface* error_icon;

Also refactor WearRecoveryUI::draw_background_locked() to get it
closer to ScreenRecoveryUI code.

Test: Build a wearable target recovery; Run graphics test.
Change-Id: I3a8d0e4dbf6fe170e4f3adde7eaf4a2043132a57
diff --git a/wear_ui.h b/wear_ui.h
index 9731f41..e97598b 100644
--- a/wear_ui.h
+++ b/wear_ui.h
@@ -25,8 +25,6 @@
  public:
   WearRecoveryUI();
 
-  bool Init(const std::string& locale) override;
-
   void SetStage(int current, int max) override;
 
   // printing messages
@@ -55,14 +53,12 @@
   void PrintV(const char*, bool, va_list) override;
 
  private:
-  GRSurface* backgroundIcon[5];
-
-  int menu_start, menu_end;
-
   void draw_background_locked() override;
   void draw_screen_locked() override;
 
   void PutChar(char);
+
+  int menu_start, menu_end;
 };
 
 #endif  // RECOVERY_WEAR_UI_H