platform/chrome: cros_usbpd_notify: Fix cros-usbpd-notify notifier

cros-usbpd-notify notifier was returning NOTIFY_BAD when no host event
was available in the MKBP message.
But MKBP messages are used to transmit other information, so return
NOTIFY_DONE instead, to allow other notifier to be called.

Fixes: ec2daf6e ("platform: chrome: Add cros-usbpd-notify driver")
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

drivers/platform/chrome/cros_usbpd_notify.c

@@ -84,7 +84,7 @@ static int cros_usbpd_notify_plat(struct notifier_block *nb,
 	u32 host_event = cros_ec_get_host_event(ec_dev);
 
 	if (!host_event)
-		return NOTIFY_BAD;
+		return NOTIFY_DONE;
 
 	if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_PD_MCU)) {
 		blocking_notifier_call_chain(&cros_usbpd_notifier_list,