drm: Make the nomodeset message less sensational

The message printed when nomodeset is present in the kernel command line
makes it look as if the parameter must never be used and it's a bad idea.

But there are valid reasons to use this parameter and the message should
not imply otherwise. Change the text to be more accurate and restrained.

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/20211112133230.1595307-7-javierm@redhat.com