When ptp timestamp is enabled in RPM, RPM will append 8B
timestamp header for all RX traffic. MCS need to skip these
8 bytes header while parsing the packet header, so that
correct tcam key is created for lookup.
This patch fixes the mcs parser configuration to skip this
8B header for ptp packets.

Fixes: ca7f49ff ("octeontx2-af: cn10k: Introduce driver for macsec block.")
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: Geetha sowjanya <gakula@marvell.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>