idpf: negotiate PTP capabilities and get PTP clock

PTP capabilities are negotiated using virtchnl command. Add get
capabilities function, direct access to read the PTP clock.
Set initial PTP capabilities exposed to the stack.

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Milena Olech <milena.olech@intel.com>
Tested-by: Willem de Bruijn <willemb@google.com>
Tested-by: Mina Almasry <almasrymina@google.com>
Tested-by: Samuel Salin <Samuel.salin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>