nvme-trace: move opcode symbol print to nvme.h

The following patches are going to provide the target-side trace which
might need these kind of macros.  It would be great if it can be shared
between host and target side both.

Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>