Allow force_emulation_prefix to be written by privileged userspace
without reloading KVM.  The param does not have any persistent affects
and is trivial to snapshot.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220830231614.3580124-28-seanjc@google.comSigned-off-by: Paolo Bonzini <pbonzini@redhat.com>