NVMe: Add pci error handlers

Requests enabling pcie aer support. Shuts down the controller on error
detected with io frozen state prior to requesting slot reset; resumes
controller after reset completes.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>