nvme: consolidate synchronous command submission helpers

nvme: consolidate synchronous command submission helpers

Note that we keep the unused timeout argument, but allow callers to
pass 0 instead of a timeout if they want the default.  This will allow
adding a timeout to the pass through path later on.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
(cherry picked from commit f705f837c58ebe1ea69dfffff4dcc234e2fbc8dd)

Orabug: 22620486
Signed-off-by: Jason Luo <zhangqing.luo@oracle.com>
Conflicts:
	drivers/block/nvme-core.c