HID: Add suport for the brightness control keys on HP keyboards

The keys are found on the keyboards bundled with HP All-In-One machines
with USB VID/PID of 04ca:004d and 04f2:1061.

Signed-off-by: Keng-Yu Lin <kengyu@canonical.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 132b001..879443b 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -834,6 +834,15 @@
 		}
 		break;
 
+	case HID_UP_HPVENDOR2:
+		set_bit(EV_REP, input->evbit);
+		switch (usage->hid & HID_USAGE) {
+		case 0x003: map_key_clear(KEY_BRIGHTNESSDOWN);	break;
+		case 0x004: map_key_clear(KEY_BRIGHTNESSUP);	break;
+		default:    goto ignore;
+		}
+		break;
+
 	case HID_UP_MSVENDOR:
 		goto ignore;