drm/edid: drop kernel-doc for static functions

Drop the kernel-doc for static functions, it's excessive, but retain the
info in plain comments.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Simon Ser <contact@emersion.fr>
Link: https://patchwork.freedesktop.org/patch/msgid/20220426091913.1339941-2-jani.nikula@intel.com