fb: Remove unused code

The FBIOGINFO ioctl was added in 1994 with the 4.4 Lite import but was commented.
Remove it.

Reviewed by: emaste
MFC after: 2 weeks
Sponsored by: Beckhoff Automation GmbH & Co. KG
Differential Revision: https://reviews.freebsd.org/D33211

(cherry picked from commit 95744d84b13ee1c34fd6d04fb3ff82cb8a34ac45)