ixgbe: PTP Fix hwtstamp mode settings

When enabling the hwtstamp mode for Rx timestamping the V2 ptp event type
specific modes (Delay Request and Sync) have been rolled into the V2 all event
packet modes, in order to more accurately represent what hardware is doing.
Hardware always timestamps the Path delay packets when a V2 mode is selected,
regardless of what type was selected (in order to always support Path delay
mode). However this means the user selected modes of timestamping only Sync or
Delay Request is not truly supported. This patch correctly sets the mode for
the hwtstamp config and returns to the user that all V2 event packets will be
timestamped.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>