net: fec: initialize clock with 0 rather than current kernel time

Initializing with 0 makes it much easier to identify time stamps from
otherwise uninitialized clock.

Initialization of PTP clock with current kernel time makes little sense as
PTP time scale differs from UTC time scale that kernel time represents.
It only leads to confusion when no actual PTP initialization happens, as
these time scales differ in a small integer number of seconds (37 at the
time of writing.)

Signed-off-by: Sergey Organov <sorganov@gmail.com>
Acked-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>