KVM: x86: remove unnecessary arguments from complete_emulator_pio_in

complete_emulator_pio_in can expect that vcpu->arch.pio has been filled in,
and therefore does not need the size and count arguments.  This makes things
nicer when the function is called directly from a complete_userspace_io
callback.

No functional change intended.

Cc: stable@vger.kernel.org
Fixes: 7ed9abfe ("KVM: SVM: Support string IO operations for an SEV-ES guest")
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>