arch, cpu, dev, gpu, mem, sim, python: start using getPort.

Replace the getMasterPort, getSlavePort, and getEthPort functions
with getPort, and remove extraneous mechanisms that are no longer
necessary.

Change-Id: Iab7e3c02d2f3a0cf33e7e824e18c28646b5bc318
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17040
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

src/sim/SConscript

@@ -55,6 +55,7 @@ Source('init.cc', add_tags='python')
 Source('init_signals.cc')
 Source('main.cc', tags='main')
 Source('port.cc')
+Source('python.cc', add_tags='python')
 Source('root.cc')
 Source('serialize.cc')
 Source('drain.cc')