kvmvapic: Remove user_creatable flag

kvmvapic: Remove user_creatable flag

The kvmvapic device is only usable when created by
apic_common_realize(), not using -device. Remove the
user_creatable flag from the device class.

Cc: Igor Mammedov <[email protected]>
Cc: Marcel Apfelbaum <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: Eduardo Habkost <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Acked-by: Marcel Apfelbaum <[email protected]>
Signed-off-by: Eduardo Habkost <[email protected]>
Message-Id: <20170503203604[email protected]>
Signed-off-by: Eduardo Habkost <[email protected]>