nfp: extend NSP infrastructure for configurable timeouts

The firmware flashing NSP operation takes longer to execute than the
current default timeout. We need a mechanism to set a longer timeout for
some commands. This patch adds the infrastructure to this.

The default timeout is still 30 seconds.

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