fb: Remove unused FBIOSVIDEO/FBIOGVIDEO ioctls

The FBIOSVIDEO/FBIOGVIDEO ioctls were added in 1994 with the 4.4 Lite import
but were never implemented in either sc(4), fb(4) or vt(4).
Remove it.

Reviewed by: emaste, tsoome
MFC after: 2 weeks
Sponsored by: Beckhoff Automation GmbH & Co. KG
Differential Revision: https://reviews.freebsd.org/D33216

(cherry picked from commit 26542b33a4d5e06a26bd9ea523c1087d75c0c41a)