nvme: Remove duplicate command printing routine

Both nvme_dump_command and nvme_qpair_print_command print nvme
commands. The former latter better. Recode the one call to
nvme_dump_command to use nvme_qpair_print_command and delete the
former. No sense having two nearly identical routines. A future commit
will convert to sbuf.

Sponsored by: Netflix
Reviewed by: chuck, mav, jhb
Differential Revision: https://reviews.freebsd.org/D41309