openamp: add ns_unbind_cb to rpmsg_device

it's useful to notify the port layer and
also symmetry with ns_bind_cb callback

Signed-off-by: ligd <liguiding1@xiaomi.com>

Author: GUIDINGLI

lib/include/openamp/rpmsg.h

@@ -118,6 +118,7 @@ struct rpmsg_device {
 	unsigned long bitmap[metal_bitmap_longs(RPMSG_ADDR_BMP_SIZE)];
 	metal_mutex_t lock;
 	rpmsg_ns_bind_cb ns_bind_cb;
+	rpmsg_ns_bind_cb ns_unbind_cb;
 	struct rpmsg_device_ops ops;
 	bool support_ns;
 };

lib/rpmsg/rpmsg_virtio.c

@@ -584,6 +584,8 @@ static int rpmsg_virtio_ns_callback(struct rpmsg_endpoint *ept, void *data,
 		metal_mutex_release(&rdev->lock);
 		if (_ept && _ept->ns_unbind_cb)
 			_ept->ns_unbind_cb(_ept);
+		if (rdev->ns_unbind_cb)
+			rdev->ns_unbind_cb(rdev, name, dest);
 	} else {
 		if (!_ept) {
 			/*