KVM: SVM: Add a missing 'break' statement

Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Fixes: f6511935

 ("KVM: SVM: Add checks for IO instructions")
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>