net/bnx2x: fix segfaults due to stale interrupt status

net/bnx2x: fix segfaults due to stale interrupt status

Previous ungraceful exit may leave behind un-acked stale
interrupts for slowpath and fastpath.

Interrupt status polling function is started before FLR is
initiated, so we don't have a real way to protect this polling
function invoking an interrupt handler caused due to stale
interrupt status from previous ungraceful exit.

So, check uninitialized status block variables in interrupt
handling path which may lead to segfault.

Fixes: 540a211084a7 ("bnx2x: driver core")
Cc: stable@dpdk.org
Signed-off-by: Shahed Shaikh <shshaikh@marvell.com>