octeontx2-bphy-netdev: cnf105xxn: fix ptp timestamp in master mode

commit 3c896308fb1d721b2d402ab047bce727ef969b1e from
git@git.assembla.com:cavium/WindRiver.linux.git

In cnf105xxn, when BCN offset is used for PTP timestamp calculation,
there is no need to use SW timecounter offset calculation. The BCN
clock will be initialized to GPS epoch. This patch fixes the problem.

Change-Id: Idb515ddc1e515a077b48d605ebf08ead81027836
Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
Reviewed-on: https://sj1git1.cavium.com/c/IP/SW/kernel/linux/+/86941


Reviewed-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Tested-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: Ruiqiang Hao <Ruiqiang.Hao@windriver.com>