target-arm: kvm64: set guest PMUv3 feature bit if supported

Check if kvm supports guest PMUv3. If so, set the corresponding feature
bit for vcpu.

Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Message-id: 1465267577-1808-2-git-send-email-zhaoshenglong@huawei.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
