nvme-pci: Fix nvme queue cleanup if IRQ setup fails

This patch fixes nvme queue cleanup if requesting an IRQ handler for
the queue's vector fails. It does this by resetting the cq_vector to
the uninitialized value of -1 so it is ignored for a controller reset.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
[changelog updates, removed misc whitespace changes]
Signed-off-by: Keith Busch <keith.busch@intel.com>