Cleanup of WaveshareInterface

-Removed update_and_display_frame
-removed update_and_display_partial_frame

-Renamed get_width and get_height to just width and height

src/epd4in2/mod.rs

@@ -291,11 +291,11 @@ where
         &self.color
     }
 
-    fn get_width(&self) -> u16 {
+    fn width(&self) -> u16 {
         WIDTH
     }
 
-    fn get_height(&self) -> u16 {
+    fn height(&self) -> u16 {
         HEIGHT
     }