nfp: update Agilio SmartNIC flower firmware to rev AOTC-2.12.A.13

This is a small bugfix release, most notably improving link state
stability in certain cases.

Signed-off-by: Louis Peens <louis.peens@netronome.com>
Tested-by: Charles Murcott <charles.murcott@netronome.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>