KVM: SEV-ES: reuse advance_sev_es_emulated_ins for OUT too

complete_emulator_pio_in() only has to be called by
complete_sev_es_emulated_ins() now; therefore, all that the function does
now is adjust sev_pio_count and sev_pio_data.  Which is the same for
both IN and OUT.

No functional change intended.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>