gve: Add initial PTP device support

If the device supports reading of the nic clock, add support
to initialize and register the PTP clock.

Signed-off-by: Ziwei Xiao <ziweixiao@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
Link: https://patch.msgid.link/20250614000754.164827-4-hramamurthy@google.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>