input: button_kbd: make driver complementary to gpio buttons

Remove need of dts binding for button keyboard since it reuses
gpio-keys binding. Select gpio-keys driver if button keyboard
is selected since button keyboard can not operate on its own.

Tested-by: Svyatoslav Ryhel <clamor95@gmail.com> # HTC One X T30
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/input/button_kbd.c b/drivers/input/button_kbd.c
index 99e65f1..74fadfc 100644
--- a/drivers/input/button_kbd.c
+++ b/drivers/input/button_kbd.c
@@ -111,16 +111,14 @@
 	return 0;
 }
 
-static const struct udevice_id button_kbd_ids[] = {
-	{ .compatible = "button-kbd" },
-	{ }
-};
-
 U_BOOT_DRIVER(button_kbd) = {
 	.name		= "button_kbd",
 	.id		= UCLASS_KEYBOARD,
-	.of_match	= button_kbd_ids,
 	.ops		= &button_kbd_ops,
 	.priv_auto	= sizeof(struct button_kbd_priv),
 	.probe		= button_kbd_probe,
 };
+
+U_BOOT_DRVINFO(button_kbd) = {
+	.name = "button_kbd"
+};