msm: emac: Report time delta of next PTP pulse in sysfs

Change the reporting format of sysfs node to show the next EMAC
PTP pulse to avoid confusion. The combination of the third
and forth field shows the time delta until the next pulse.

Change-Id: Ib11bd43c38bf5423b4ca68c917a7a244d3cee3ae
Acked-by: Jie Luo <jluo@qti.qualcomm.com>
Signed-off-by: Gilad Avidov <gavidov@codeaurora.org>