ionic: catch NULL pointer issue on reconfig

ionic: catch NULL pointer issue on reconfig

It's possible that the driver will dereference a qcq that doesn't exist
when calling ionic_reconfigure_queues(), which causes a page fault BUG.

If a reduction in the number of queues is followed by a different
reconfig such as changing the ring size, the driver can hit a NULL
pointer when trying to clean up non-existent queues.

Fix this by checking to make sure both the qcqs array and qcq entry
exists bofore trying to use and free the entry.

Fixes: 101b40a0171f ("ionic: change queue count with no reset")
Signed-off-by: Brett Creeley <brett@pensando.io>
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Link: https://lore.kernel.org/r/20221017233123.15869-1-snelson@pensando.io
Signed-off-by: Jakub Kicinski <kuba@kernel.org>