nSVM: Remove a superfluous modification of guest EFER.NX in NPT NX test

Remove a bizarre modification of the guest's EFER.NX from the NPT NX
test.  For reasons unknown, the NPT NX test forces EFER.NX in the guest
_after_ running the test.  Now that the v1 infrastructure saves/restores
guest EFER across the test, the motivation, whatever thay may have been,
is moot because the forced EFER.NX value won't persist.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210622210047.3691840-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>