ptp: lan743x: Use spin_lock instead of spin_lock_bh

lan743x_ptp_request_tx_timestamp uses spin_lock_bh, but it is
only called from lan743x_tx_xmit_frame where all IRQs are
already disabled.

This fixes the "IRQs not enabled as expected" warning.

Signed-off-by: Lucas Tanure <tanure@linux.com>
Link: https://lore.kernel.org/r/20240128101849.107298-1-tanure@linux.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/microchip/lan743x_ptp.c

@@ -1712,13 +1712,13 @@ bool lan743x_ptp_request_tx_timestamp(struct lan743x_adapter *adapter)
 	struct lan743x_ptp *ptp = &adapter->ptp;
 	bool result = false;
 
-	spin_lock_bh(&ptp->tx_ts_lock);
+	spin_lock(&ptp->tx_ts_lock);
 	if (ptp->pending_tx_timestamps < LAN743X_PTP_NUMBER_OF_TX_TIMESTAMPS) {
 		/* request granted */
 		ptp->pending_tx_timestamps++;
 		result = true;
 	}
-	spin_unlock_bh(&ptp->tx_ts_lock);
+	spin_unlock(&ptp->tx_ts_lock);
 	return result;
 }