KVM: SVM: sync TPR value to V_TPR field in the VMCB

This patch adds syncing of the lapic.tpr field to the V_TPR field of the VMCB.
With this change we can safely remove the CR8 read intercept.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>