Add teken_subr_do_resize new method, to update taken sizes w/o reset positions
and use it in case we update terminal size not touching existing data.

Sponsored by:	The FreeBSD Foundation
Define fb newbus interface to connect framebuffer providers with fbd.

Sponsored by:	The FreeBSD Foundation
Allow fbd to be attached as newbus device.

Sponsored by:	The FreeBSD Foundation
o Add fb_getinfo method.
o Attach fbd.
o Comments other possible ways to attach fbd. (Should be moved to man page).

Sponsored by:	The FreeBSD Foundation