platform/x86: intel-vbtn: Log event code on unexpected button events

When logging the warning about receiving a button event on a device
without buttons log the event code which triggered the warning.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Link: https://lore.kernel.org/r/20240327195712.43851-1-hdegoede@redhat.com