ionic: remove unnecessary compat ifdef

We don't need to look for HAVE_HWSTAMP_TX_ONESTEP_P2P in the
upstream kernel.
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/pensando/ionic/ionic_phc.c

@@ -18,10 +18,8 @@ static int ionic_hwstamp_tx_mode(int config_tx_type)
 		return IONIC_TXSTAMP_ON;
 	case HWTSTAMP_TX_ONESTEP_SYNC:
 		return IONIC_TXSTAMP_ONESTEP_SYNC;
-#ifdef HAVE_HWSTAMP_TX_ONESTEP_P2P
 	case HWTSTAMP_TX_ONESTEP_P2P:
 		return IONIC_TXSTAMP_ONESTEP_P2P;
-#endif
 	default:
 		return -ERANGE;
 	}