octeontx2-bphy-netdev: cnf10k: don't modify pps threshold when sw timecounter is not used

commit 589e6749add582de8f45d170e50334bf3e3389ef from
git@git.assembla.com:cavium/WindRiver.linux.git

Don't modify PPS threshold registers when SW timecounter is not used since
PTP timestamp is entirely maintained in HW registers. When PPS errata is
present, the SW workaround is ineffective when PPS threshold registers are
modified.

Change-Id: Ifb267a0806732a1de5233cbdfab9d4093f412e01
Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
Reviewed-on: https://sj1git1.cavium.com/c/IP/SW/kernel/linux/+/100783
Tested-by: sa_ip-sw-jenkins <sa_ip-sw-jenkins@marvell.com>
Reviewed-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: Ruiqiang Hao <Ruiqiang.Hao@windriver.com>