Reinit avalon device in case of FPGA controller mess up.

driver-avalon.c

@@ -918,6 +918,8 @@ static int64_t avalon_scanhash(struct thr_info *thr, struct work **work,
 		applog(LOG_ERR,
 		       "AVA%i: FPGA controller mess up", avalon->device_id);
 		dev_error(avalon, REASON_DEV_COMMS_ERROR);
+		do_avalon_close(thr);
+		avalon_init(avalon);
 		return 0;
 	}