octeontx2-af: cn10k: RPM hardware timestamp configuration

MAC on CN10K support hardware timestamping such that 8 bytes addition
header is prepended to incoming packets. This patch does necessary
configuration to enable Hardware time stamping upon receiving request
from PF netdev interfaces.

Timestamp configuration is different on MAC (CGX) Octeontx2 silicon
and MAC (RPM) OcteonTX3 CN10k. Based on silicon variant appropriate
fn() pointer is called. Refactor MAC specific mbox messages to remove
unnecessary gaps in mboxids.

Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>