HID: apple: Set APPLE_ISO_KEYBOARD at USB_DEVICE_ID_APPLE_GEYSER4_HF_ISO

Set APPLE_ISO_KEYBOARD flag on USB_DEVICE_ID_APPLE_GEYSER4_HF_ISO so we get
the ISO translation on German keyboards for the MacBook4,1 as well.

Signed-off-by: Johannes Thumshirn <morbidrsa@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>