platform/x86: asus-wmi: Make kbd_rgb_mode_groups static

kbd_rgb_mode_groups is only used inside asus-wmi.c, make it static.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20220909210950.385398-1-hdegoede@redhat.com