package/kodi: add comment to display udev dependency for gbm when wayland/x11 are disabled

Without this additional comment only the comment

  kodi needs an OpenGL EGL backend with OpenGL or GLES support

is displayed which is not enough to guide users.

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>