efifb: Remove redundant efifb_setup_from_dmi stub

efifb is the only user of efifb_setup_from_dmi which is provided by
sysfb which is selected by efifb. That makes the stub redundant.

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/7416c439d68e9e96068ea5c77e05c99c7df41750.1645822213.git.msuchanek@suse.de