mac802154: tx: add support for xmit_async callback

This patch renames the existsing xmit callback to xmit_sync and
introduces an asynchronous xmit_async function. If ieee802154_ops
doesn't provide the xmit_async callback, then we have a fallback to
the xmit_sync callback.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Cc: Alan Ott <alan@signal11.us>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/drivers/net/ieee802154/mrf24j40.c b/drivers/net/ieee802154/mrf24j40.c
index 2e267c5..3d775af 100644
--- a/drivers/net/ieee802154/mrf24j40.c
+++ b/drivers/net/ieee802154/mrf24j40.c
@@ -581,7 +581,7 @@
 
 static struct ieee802154_ops mrf24j40_ops = {
 	.owner = THIS_MODULE,
-	.xmit = mrf24j40_tx,
+	.xmit_sync = mrf24j40_tx,
 	.ed = mrf24j40_ed,
 	.start = mrf24j40_start,
 	.stop = mrf24j40_stop,