ptp: ocp: add TOD debug information

TOD information is currently displayed only on module load,
which doesn't provide updated information as the system runs.

Create a debug file which provides the current TOD status information,
and move the information display there.

Signed-off-by: Vadim Fedorenko <vadfed@fb.com>
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>