wil6210: more debug info for vring

print used/available counters on debugfs;
print to dmesg when Tx vring becomes empty

This aids with performance investigation

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/wil6210/txrx.c b/drivers/net/wireless/ath/wil6210/txrx.c
index 0784ef3..c08d041 100644
--- a/drivers/net/wireless/ath/wil6210/txrx.c
+++ b/drivers/net/wireless/ath/wil6210/txrx.c
@@ -1132,6 +1132,10 @@
 			done++;
 		}
 	}
+
+	if (wil_vring_is_empty(vring))
+		wil_dbg_txrx(wil, "Ring[%2d] empty\n", ringid);
+
 	if (wil_vring_avail_tx(vring) > wil_vring_wmark_high(vring))
 		netif_tx_wake_all_queues(wil_to_ndev(wil));