In order to use inclusive terminology, rename 'slave stream'
as 'sink stream'.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-Id: <20200910070131.435543-5-philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>