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%2FFI4EJezcfd1@gmail.com/
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Fixes: 056bce6 ("bnxt_en: Make PTP TX timestamp HWRM query silent")
Link: https://lore.kernel.org/r/20240125134104.2045573-1-leitao@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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);
 	}