Revert "KVM: VMX: Save HOST_CR3 in vmx_set_host_fs_gs()"

Revert "KVM: VMX: Save HOST_CR3 in vmx_set_host_fs_gs()"

Undo a nested VMX fix as a step toward reverting the commit it fixed,
204ace71bed8 ("KVM: VMX: Save HOST_CR3 in vmx_prepare_switch_to_guest()"),
as the underlying premise that "host CR3 in the vcpu thread can only be
changed when scheduling" is wrong.

This reverts commit c82796df27a5aea057d20e4a878cc4a122a22e16.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220224191917.3508476-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>