octeontx2-af: Initialize PTP_SEC_ROLLOVER register properly

Since the reset value of PTP_SEC_ROLLOVER is incorrect on
CNF10KB silicon, the ptp timestamps are inaccurate. This
patch initializes the PTP_SEC_ROLLOVER register properly
for the CNF10KB silicon.

Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
Signed-off-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>