octeontx2-pf: cn10k: add support for new ptp timestamp format

The cn10k hardware ptp timestamp format has been modified primarily
to support 1-step ptp clock. The 64-bit timestamp used by hardware is
split into two 32-bit fields, the upper one holds seconds, the lower
one nanoseconds. A new register (PTP_CLOCK_SEC) has been added that
returns the current seconds value. The nanoseconds register PTP_CLOCK_HI
resets after every second. The cn10k RPM block provides Rx/Tx timestamps
to the NIX block using the new timestamp format. The software can read
the current timestamp in nanoseconds by reading both PTP_CLOCK_SEC &
PTP_CLOCK_HI registers.

This patch provides support for new timestamp format.

Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
Signed-off-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: Rakesh Babu Saladi <rsaladi2@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>