nvmecontrol: Fix default ns create parameters.

Instead of passing 0xff's for all unset parameters, prefer reasonable
defaults. It is much easier to use it this was without specs in hand.

PR: 269912
Approved by: re (cperciva)
(cherry picked from commit 20dc2c4d11ddaa980c491116b65c51ab522028e9)
(cherry picked from commit de0b02cb7b112947191af96dd34e7a95b760019c)