cciss: Fallback to MSI rather than to INTx if MSI-X failed

Currently the driver falls back to INTx mode when MSI-X
initialization failed. This is a suboptimal behaviour
for chips that also support MSI. This update changes that
behaviour and falls back to MSI mode in case MSI-X mode
initialization failed.

Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Cc: Mike Miller <mike.miller@hp.com>
Cc: iss_storagedev@hp.com
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-pci@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>