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

drivers/platform/x86/asus-wmi.c

@@ -835,7 +835,7 @@ static const struct attribute_group kbd_rgb_state_group = {
 	.attrs = kbd_rgb_state_attrs,
 };
 
-const struct attribute_group *kbd_rgb_mode_groups[] = {
+static const struct attribute_group *kbd_rgb_mode_groups[] = {
 	NULL,
 	NULL,
 	NULL,