ptp: stmmac: use helpers for converting ns to timespec.

This patch changes the driver to use ns_to_timespec64() instead of
open coding the same logic.

Compile tested only.
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c

@@ -111,7 +111,6 @@ static int stmmac_get_time(struct ptp_clock_info *ptp, struct timespec64 *ts)
 	    container_of(ptp, struct stmmac_priv, ptp_clock_ops);
 	unsigned long flags;
 	u64 ns;
-	u32 reminder;
 
 	spin_lock_irqsave(&priv->ptp_lock, flags);
 
@@ -119,8 +118,7 @@ static int stmmac_get_time(struct ptp_clock_info *ptp, struct timespec64 *ts)
 
 	spin_unlock_irqrestore(&priv->ptp_lock, flags);
 
-	ts->tv_sec = div_u64_rem(ns, 1000000000ULL, &reminder);
-	ts->tv_nsec = reminder;
+	*ts = ns_to_timespec64(ns);
 
 	return 0;
 }