fbdev: Remove FBINFO_DEFAULT and FBINFO_FLAG_DEFAULT

Remove the unused flags FBINFO_DEFAULT and FBINFO_FLAG_DEFAULT. No
functional changes.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Helge Deller <deller@gmx.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230715185343.7193-18-tzimmermann@suse.de