media: vivid: Move all fb_info references into vivid-osd

Most references to fb_info are already within vivid-osd.c. This patch
moves the remaining references into vivid-osd.c.

We also take this opportunity to make the function names in vivid-osd
more consistent.

This is a preparation patch to make CONFIG_FB optional for vivid.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>