Remove the redundant svm_sev_enabled() check when calling
sev_hardware_teardown(), the teardown helper itself does the check.
Removing the check from svm.c will eventually allow dropping
svm_sev_enabled() entirely.

No functional change intended.

Reviewed by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: NBrijesh Singh <brijesh.singh@amd.com>
Signed-off-by: NSean Christopherson <seanjc@google.com>
Message-Id: <20210422021125.3417167-11-seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>