This replaces getNetinfoSinkWire with 3 new functions for different use
cases.
At the moment all existing code has been moved to getNetinfoSinkWire
with phys_idx=0 so the build doesn't break; but this won't yet function
properly with more than one sink. But it provides a base on which to
work on refactoring the routers to support this case.
Signed-off-by: gatecat <gatecat@ds0.me>
