Remove frontstuff
Nothing implements this in the tree. Remove the ioctl and the
conversion to the geom atttribute stuff.
This was introduced in r94287 in 2002 and was retired in r113390
- It appeared in FreeBSD 5.0, but no other releases. This is a
vestige that was missed at the time and overlooked until now. No
compat is provided for this reason. And there's no implementation of
it today. And it was never part of a release from a stable branch.
Reviewed by: phk@
Differential Revision: https://reviews.freebsd.org/D26967