at86rf230: fix callback for aret handling

This patch fix the complete callback for going into aret on. Currently
we starting after a state change into aret on again a state change into
aret on which is not necessary.
Signed-off-by: NAlexander Aring <alex.aring@gmail.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

drivers/net/ieee802154/at86rf230.c

@@ -1013,7 +1013,7 @@ at86rf230_xmit_start(void *context)
 		if (lp->is_tx_from_off) {
 			lp->is_tx_from_off = false;
 			at86rf230_async_state_change(lp, ctx, STATE_TX_ARET_ON,
-						     at86rf230_xmit_tx_on,
+						     at86rf230_write_frame,
 						     false);
 		} else {
 			at86rf230_async_state_change(lp, ctx, STATE_TX_ON,