xilinx_axi*: Re-implemented interconnect

Re-implemented the interconnect between the Xilinx AXI ethernet and DMA
controllers. A QOM interface "stream" is created, for the two stream interfaces.

As per Edgars request, this is designed to be more generic than AXI-stream,
so in the future we may see more clients of this interface beyond AXI stream.

This is based primarily on Paolos original refactoring of the interconnect.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter A.G. Crosthwaite <peter.crosthwaite@petalogix.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>

hw/stream.c

@@ -0,0 +1,23 @@
+#include "stream.h"
+
+void
+stream_push(StreamSlave *sink, uint8_t *buf, size_t len, uint32_t *app)
+{
+    StreamSlaveClass *k =  STREAM_SLAVE_GET_CLASS(sink);
+
+    k->push(sink, buf, len, app);
+}
+
+static TypeInfo stream_slave_info = {
+    .name          = TYPE_STREAM_SLAVE,
+    .parent        = TYPE_INTERFACE,
+    .class_size = sizeof(StreamSlaveClass),
+};
+
+
+static void stream_slave_register_types(void)
+{
+    type_register_static(&stream_slave_info);
+}
+
+type_init(stream_slave_register_types)