net: fec_ptp: Use platform_get_irq_xxx_optional() to avoid error message

Use platform_get_irq_byname_optional() and platform_get_irq_optional()
instead of platform_get_irq_byname() and platform_get_irq() for optional
IRQs to avoid below error message during probe:

[    0.795803] fec 30be0000.ethernet: IRQ pps not found
[    0.800787] fec 30be0000.ethernet: IRQ index 3 not found
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Acked-by: Fugang Duan <fugang.duan@nxp.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/fec_ptp.c

@@ -600,9 +600,9 @@ void fec_ptp_init(struct platform_device *pdev, int irq_idx)
 
 	INIT_DELAYED_WORK(&fep->time_keep, fec_time_keep);
 
-	irq = platform_get_irq_byname(pdev, "pps");
+	irq = platform_get_irq_byname_optional(pdev, "pps");
 	if (irq < 0)
-		irq = platform_get_irq(pdev, irq_idx);
+		irq = platform_get_irq_optional(pdev, irq_idx);
 	/* Failure to get an irq is not fatal,
 	 * only the PTP_CLOCK_PPS clock events should stop
 	 */