nvme: Introduce longer timeouts for admin queue

KIOXIA CD8 SSDs routinely take ~25 seconds to delete non-empty
namespace. In some cases like hot-plug it takes longer, triggering
timeout and controller resets after just 30 seconds. Linux for many
years has separate 60 seconds timeout for admin queue. This patch
does the same. And it is good to be consistent.

Sponsored by: iXsystems, Inc.
Reviewed by: imp
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D42454