drm/fb-helper: Export drm_fb_helper_release_info()

Export the fb_info release code as drm_fb_helper_release_info(). Will
help with cleaning up failed fbdev probing.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Zack Rusin <zackr@vmware.com>
Tested-by: Sui <Jingfeng&lt;suijingfeng@loongson.cn>
Link: https://patchwork.freedesktop.org/patch/msgid/20230320150751.20399-4-tzimmermann@suse.de