ixl(4): Fix reporting of unqualified transceivers

When link_active_on_if_down flag is disabled and link is brought down
with ifconfig, FW reports a false positive link event about an
unqualified transceiver. The condition used in the driver to filter out
those false positive events was incorrect and caused that unqualified
module event to also not be reported when the event was valid.

Change the condition to rely on IFF_UP flag instead of
link_active_on_if_down and bump driver version to 2.3.1-k.

Signed-off-by: Krzysztof Galazka <krzysztof.galazka@intel.com>
Signed-off-by: Eric Joyner <erj@FreeBSD.org>

Reviewed by: stallamr@netapp.com, erj@
Tested by: gowtham.kumar.ks@intel.com
Sponsored by: Intel Corporation
Differential Revision: https://reviews.freebsd.org/D30733

(cherry picked from commit c4622b01d2f12b889b57ff7d0b03a38dfcb00fd8)