nvme: add a common helper to read Identify Controller data

And add the 64-bit register read operation for it.

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