KVM: SVM: Fix memory leaks that happen when svm_create_vcpu() fails

svm_create_vcpu() does not free the pages allocated during the creation
when it fails to complete the allocations. This patch fixes it.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>