nfp: clear ring delayed kick counters

We need to clear delayed kick counters when we free rings otherwise
after ndo_close()/ndo_open() we could kick HW by more entries than
actually written to rings.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Rolf Neugebauer <rolf.neugebauer@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>