Android: fix/ignore L2/R2 buttons

L2/R2 will trigger a key press and an axis event if the trigger is pressed fully down
Was incorrectly ignoring L1/R1 key presses.

Original commit by zackhow for Dolphin-emu.

src/android/app/src/main/java/org/citra/citra_emu/utils/ControllerMappingHelper.java

@@ -15,8 +15,7 @@ public class ControllerMappingHelper {
         if (isDualShock4(inputDevice)) {
             // The two analog triggers generate analog motion events as well as a keycode.
             // We always prefer to use the analog values, so throw away the button press
-            // Even though the triggers are L/R2, without mappings they generate L/R1 events.
-            return keyCode == KeyEvent.KEYCODE_BUTTON_L1 || keyCode == KeyEvent.KEYCODE_BUTTON_R1;
+            return keyCode == KeyEvent.KEYCODE_BUTTON_L2 || keyCode == KeyEvent.KEYCODE_BUTTON_R2;
         }
         return false;
     }