ena: Update driver version to v2.6.3
Bug Fixes:
- Initialize statistics before the interface is available
- Fix driver unload crash
Minor Changes:
- Mechanically convert ena(4) to DrvAPI
- Remove usage of IFF_KNOWSEPOCH
MFC after: 2 weeks
Sponsored by: Amazon, Inc.
(cherry picked from commit ac40021c935d77d86e68d28c6d33187ce9638ec6)