MAINTAINERS: add drivers/ptp/ptp_qoriq_debugfs.c into QorIQ PTP list

Added drivers/ptp/ptp_qoriq_debugfs.c into QorIQ PTP clock driver list.
Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

MAINTAINERS

@@ -6087,6 +6087,7 @@ M:	Yangbo Lu <yangbo.lu@nxp.com>
 L:	netdev@vger.kernel.org
 S:	Maintained
 F:	drivers/ptp/ptp_qoriq.c
+F:	drivers/ptp/ptp_qoriq_debugfs.c
 F:	include/linux/fsl/ptp_qoriq.h
 F:	Documentation/devicetree/bindings/ptp/ptp-qoriq.txt