ath6kl: fix busreqs so they can be reused when sg is cleaned up

To reuse the busreqs in case of hardware restart, they must be
properly reinitialized.  If the scat_req pointer isn't reset to
0, __ath6kl_sdio_write_async() will assume there is sg work to be
done (causing a kernel OOPS).
Signed-off-by: James Minor <james.minor@ni.com>
Reviewed-by: Steve deRosier <steve.derosier@lairdtech.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath6kl/sdio.c

@@ -703,8 +703,10 @@ static void ath6kl_sdio_cleanup_scatter(struct ath6kl *ar)
 		 * ath6kl_hif_rw_comp_handler() with status -ECANCELED so
 		 * that the packet is properly freed?
 		 */
-		if (s_req->busrequest)
+		if (s_req->busrequest) {
+			s_req->busrequest->scat_req = 0;
 			ath6kl_sdio_free_bus_req(ar_sdio, s_req->busrequest);
+		}
 		kfree(s_req->virt_dma_buf);
 		kfree(s_req->sgentries);
 		kfree(s_req);