drm/fbdev: Remove aperture handling and FBINFO_MISC_FIRMWARE

There are no users left of struct fb_info.apertures and the flag
FBINFO_MISC_FIRMWARE. Remove both and the aperture-ownership code
in the fbdev core. All code for aperture ownership is now located
in the fbdev drivers.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221219160516.23436-19-tzimmermann@suse.de