net: dcbnl: Add IEEE app selector value definitions

This adds defines for the app selector values currently
defined in the IEEE 802.1Qaz specification.

Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>