bsdinstall: fix vfs.zfs.vdev.min_auto_ashift oid

Signed-off-by: Siva Mahadevan <me@svmhdvn.name>
PR: 266374
Pull request: https://github.com/freebsd/freebsd-src/pull/1851
Reviewed by: emaste
Sponsored by: The FreeBSD Foundation

(cherry picked from commit 87a7b35f04b60956e9aa192680ae80773ec38f14)
(cherry picked from commit 093f3f26e95198bf1db082763e915d7a53c6ba82)
(cherry picked from commit 8f7dded412516d35e538ed05524d2a14870e62b0)