KVM: Replace reads of vcpu->arch.cr3 by an accessor

This allows us to keep cr3 in the VMCS, later on.

Signed-off-by: Avi Kivity <avi@redhat.com>

diff --cc arch/x86/kvm/kvm_cache_regs.h
Simple merge

diff --cc arch/x86/kvm/mmu.c
Simple merge

diff --cc arch/x86/kvm/svm.c
Simple merge

diff --cc arch/x86/kvm/vmx.c
Simple merge

diff --cc arch/x86/kvm/x86.c
Simple merge