bnxt_en: Make PTP timestamp HWRM more silent

commit 056bce6 ("bnxt_en: Make PTP TX timestamp HWRM query silent")
changed a netdev_err() to netdev_WARN_ONCE().

netdev_WARN_ONCE() is it generates a kernel WARNING, which is bad, for
the following reasons:

 * You do not a kernel warning if the firmware queries are late
 * In busy networks, timestamp query failures fairly regularly
 * A WARNING message doesn't bring much value, since the code path
is clear.
(This was discussed in-depth in [1])

Transform the netdev_WARN_ONCE() into a netdev_warn_once(), and print a
more well-behaved message, instead of a full WARN().

	bnxt_en 0000:67:00.0 eth0: TS query for TX timer failed rc = fffffff5

[1] Link: https://lore.kernel.org/all/ZbDj%[email protected]/
Signed-off-by: Breno Leitao <[email protected]>
Reviewed-by: Pavan Chebbi <[email protected]>
Reviewed-by: Michael Chan <[email protected]>
Fixes: 056bce6 ("bnxt_en: Make PTP TX timestamp HWRM query silent")
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: leitao

drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c

@@ -684,7 +684,7 @@ static void bnxt_stamp_tx_skb(struct bnxt *bp, struct sk_buff *skb)
 		timestamp.hwtstamp = ns_to_ktime(ns);
 		skb_tstamp_tx(ptp->tx_skb, &timestamp);
 	} else {
-		netdev_WARN_ONCE(bp->dev,
+		netdev_warn_once(bp->dev,
 				 "TS query for TX timer failed rc = %x\n", rc);
 	}