net: lan743x_ptp: convert to ktime_get_clocktai_ts64

timekeeping_clocktai64() has been renamed to ktime_get_clocktai_ts64()
for consistency with the other ktime_get_* access functions.

Rename the new caller that has come up as well.

Question: this is the only ptp driver that sets the hardware time
to the current system time in TAI. Why does it do that?

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>