Merged in antmerlino/nuttx/mac802154_ackhandling (pull request #619)

mac802154: Adds ackreq flag to TX descriptor for use by radio driver.

The radio layer is responsible for a full "transaction". Because of
differences in radio capabilites, the radio must be responsible for
the handling of acks and retransmissions. This commit simply passes
the ackreq meta-data flag along to the radio.

Approved-by: Gregory Nutt <gnutt@nuttx.org>

include/nuttx/wireless/ieee802154/ieee802154_radio.h

@@ -84,6 +84,7 @@ struct ieee802154_txdesc_s
 
   enum ieee802154_frametype_e frametype;
 
+  bool ackreq;          /* Are we requesting an ACK? */
   bool framepending;    /* Did the ACK have the frame pending bit set */
   uint32_t purgetime;   /* Time to purge transaction */
   uint8_t  retrycount;  /* Number of remaining retries. Set to macMaxFrameRetries

wireless/ieee802154/mac802154_data.c

@@ -258,6 +258,7 @@ int mac802154_req_data(MACHANDLE mac,
   txdesc->conf->handle = meta->handle;
   txdesc->frame = frame;
   txdesc->frametype = IEEE802154_FRAME_DATA;
+  txdesc->ackreq = meta->flags.ackreq;
 
   /* If the TxOptions parameter specifies that a GTS transmission is required,
    * the MAC sublayer will determine whether it has a valid GTS as described