drm: Decouple nomodeset from CONFIG_VGA_CONSOLE

This relationship was only for historical reasons and the nomodeset option
should be available even on platforms that don't enable CONFIG_VGA_CONSOLE.

Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211112133230.1595307-5-javierm@redhat.com