vfio-mdev/mdpy-fb: Do not set struct fb_info.apertures

Generic fbdev drivers use the apertures field in struct fb_info to
control ownership of the framebuffer memory and graphics device. Do
not set the values in mdpy-fb.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221219160516.23436-10-tzimmermann@suse.de