nfp: tls: add basic statistics

Count TX TLS packets: successes, out of order, and dropped due to
missing record info.  Make sure the RX and TX completion statistics
don't share cache lines with TX ones as much as possible.  With TLS
stats they are no longer reasonably aligned.

Signed-off-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>