KVM: nVMX: do early preparation of vmcs02 before check_vmentry_postreqs()

KVM: nVMX: do early preparation of vmcs02 before check_vmentry_postreqs()

In anticipation of using vmcs02 to do early consistency checks, move
the early preparation of vmcs02 prior to checking the postreqs.  The
downside of this approach is that we'll unnecessary load vmcs02 in
the case that check_vmentry_postreqs() fails, but that is essentially
our slow path anyways (not actually slow, but it's the path we don't
really care about optimizing).

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>