nfp: fix memory leak on FW load error

Free management FW info when app FW load failed.

Fixes: eefbde7e

 ("nfp: add hwmon support")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>