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>

drivers/net/ieee802154/fakelb.c

@@ -131,7 +131,7 @@ fakelb_hw_stop(struct ieee802154_hw *hw) {
 
 static struct ieee802154_ops fakelb_ops = {
 	.owner = THIS_MODULE,
-	.xmit = fakelb_hw_xmit,
+	.xmit_sync = fakelb_hw_xmit,
 	.ed = fakelb_hw_ed,
 	.set_channel = fakelb_hw_channel,
 	.start = fakelb_hw_start,