input: button_kbd: trigger on press not release

Generally it feels much nicer to register when the button is pressed
rather than released, simply invert the state to do this.

Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
diff --git a/drivers/input/button_kbd.c b/drivers/input/button_kbd.c
index 74fadfc..726275a 100644
--- a/drivers/input/button_kbd.c
+++ b/drivers/input/button_kbd.c
@@ -75,7 +75,7 @@
 		if (state_changed) {
 			debug("%s: %d\n", uc_plat->label, code);
 			priv->old_state[i] = state;
-			input_add_keycode(input, code, state);
+			input_add_keycode(input, code, !state);
 		}
 		i++;
 	}