fb: Remove unused FBIOSATTR/FBIOGATTR ioctls

The FBIOSATTR/FBIOGATTR 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/D33215