drm/i915: Fix comment about modeset parameters

The comment mentions that the KMS is enabled by default unless either the
i915.modeset module parameter or vga_text_mode_force boot option are used.

But the latter does not exist and instead the nomodeset option was meant.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211103122809.1040754-2-javierm@redhat.com