MFC r275865:

MFC r275865:
Add configuration options to override physical and UNMAP blocks geometry.

While in most cases CTL should correctly fetch those values from backing
storages, there are some initiators (like MS SQL), that may not like large
physical block sizes, even if they are true.  For such cases allow override
fetched values with supported ones (like 4K).

git-svn-id: svn://svn.freebsd.org/base/stable/10@276179 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f