HID: asus: add keycodes for 0x6a, 0x4b, and 0xc7

These two keys are found on some models with dual display.
- 0x6a is intended for controlling the secondary screen brightness.
- 0x4b is intended for toggling the arrow keys between arrows and
  page up / page down.
This key is found on a slightly modified keyboard layout.
- 0xc7 is intended to cycle through keybvoard brightnesses (upwards) but
  there is not suitable existing code for this behaviour. Using
  `KEY_KBDILLUMTOGGLE` is different behaviour to Windows but at least
  is picked up by many desktops already.
Signed-off-by: Luke D. Jones <luke@ljones.dev>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-asus.c

@@ -884,6 +884,7 @@ static int asus_input_mapping(struct hid_device *hdev,
 		case 0xb5: asus_map_key_clear(KEY_CALC);			break;
 		case 0xc4: asus_map_key_clear(KEY_KBDILLUMUP);		break;
 		case 0xc5: asus_map_key_clear(KEY_KBDILLUMDOWN);		break;
+		case 0xc7: asus_map_key_clear(KEY_KBDILLUMTOGGLE);	break;
 
 		/* ASUS touchpad toggle */
 		case 0x6b: asus_map_key_clear(KEY_F21);			break;
@@ -912,6 +913,12 @@ static int asus_input_mapping(struct hid_device *hdev,
 		/* Fn+Right Aura mode next on N-Key keyboard */
 		case 0xb3: asus_map_key_clear(KEY_PROG3);		break;
 
+		/* Screenpad toggle on N-Key keyboard */
+		case 0x6a: asus_map_key_clear(KEY_F13);		break;
+
+		/* Arrows/Page-up/Down toggle on N-Key keyboard */
+		case 0x4b: asus_map_key_clear(KEY_F14);		break;
+
 		default:
 			/* ASUS lazily declares 256 usages, ignore the rest,
 			 * as some make the keyboard appear as a pointer device. */