idpf: add Tx timestamp flows

Add functions to request Tx timestamp for the PTP packets, read the Tx
timestamp when the completion tag for that packet is being received,
extend the Tx timestamp value and set the supported timestamping modes.

Tx timestamp is requested for the PTP packets by setting a TSYN bit and
index value in the Tx context descriptor. The driver assumption is that
the Tx timestamp value is ready to be read when the completion tag is
received. Then the driver schedules delayed work and the Tx timestamp
value read is requested through virtchnl message. At the end, the Tx
timestamp value is extended to 64-bit and provided back to the skb.

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Co-developed-by: Josh Hay <joshua.a.hay@intel.com>
Signed-off-by: Josh Hay <joshua.a.hay@intel.com>
Signed-off-by: Milena Olech <milena.olech@intel.com>
Tested-by: Samuel Salin <Samuel.salin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>