ptp_qoriq: fix NULL access if ptp dt node missing

Make sure ptp dt node exists before accessing it in case
of NULL pointer call trace.
Signed-off-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/ptp/ptp_qoriq.c

@@ -467,6 +467,9 @@ int ptp_qoriq_init(struct ptp_qoriq *ptp_qoriq, void __iomem *base,
 	unsigned long flags;
 	u32 tmr_ctrl;
 
+	if (!node)
+		return -ENODEV;
+
 	ptp_qoriq->base = base;
 	ptp_qoriq->caps = *caps;