KVM: SVM: Mark VMCB_NPT as dirty on nested VMRUN

KVM: SVM: Mark VMCB_NPT as dirty on nested VMRUN

Mark the VMCB_NPT bit as dirty in nested_vmcb02_prepare_save()
on every nested VMRUN.

If L1 changes the PAT MSR between two VMRUN instructions on the same
L1 vCPU, the g_pat field in the associated vmcb02 will change, and the
VMCB_NPT clean bit should be cleared.

Fixes: 4bb170a5430b ("KVM: nSVM: do not mark all VMCB02 fields dirty on nested vmexit")
Cc: stable@vger.kernel.org
Signed-off-by: Jim Mattson <jmattson@google.com>
Link: https://lore.kernel.org/r/20250922162935.621409-3-jmattson@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>