In the block controllers, set the default response SIDs for input and
output ports. If we don't do this, the blocks may send their responses
to other blocks' responses ports.

For example, without this change, the DDC may send an error packet to
port 0x0000, which is assigned to the DmaFIFO. With this change, the
DDC would send that packet to 0xFFFF, which isn't assigned to any other
block.