ixgbe: fix uninitialized event.type in ixgbe_ptp_check_pps_event

This patch fixes a bug in ixgbe_ptp_check_pps_event where the type was
uninitialized and could cause unknown event outcomes.

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>