KVM: nVMX: remove unnecessary code in prepare_vmcs02_rare

KVM: nVMX: remove unnecessary code in prepare_vmcs02_rare

The early vmwrite of the PDPTRs in prepare_vmcs02_rare() is redundant, because
every write it does will be performed by prepare_vmcs02() if it is actually
needed.

In any case where the emulator or the processor need the PDPTR, either
is_pae_paging() is true on vmentry, or a write of CR0, CR4 or EFER will
cause a vmexit to L0.  The next vmentry will refresh the PDPTRs in the
vmcs02 from vmcs12.

In fact, the original version[1] of what ended up being commit
c7554efc8335 ("KVM: nVMX: Copy PDPTRs to/from vmcs12 only when
necessary"), the writes in what is now prepare_vmcs02_rare() were removed.
When the mega-collection of optimizations was posted[2], the removal of
that code got dropped as a rebase good, so reinstate it.

[1] https://lore.kernel.org/all/20190507160640.4812-16-sean.j.christopherson@intel.com
[2] https://lore.kernel.org/all/1560445409-17363-31-git-send-email-pbonzini@redhat.com

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20260530165545.25599-3-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>