dev,cpu,configs: Get rid of the IntrControl device.

This vestigial device provides a thin layer of indirection between
devices and the CPUs in a system. It's basically a collection of helper
functions, but since it's a SimObject it needs to be instantiated in
python and added to configurations.

Change-Id: I029d2314ae0bb890678e1e68dafcdab4bfe49beb
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/43347
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/dev/Platform.py

@@ -32,7 +32,7 @@ class Platform(SimObject):
     type = 'Platform'
     abstract = True
     cxx_header = "dev/platform.hh"
-    intrctrl = Param.IntrControl(Parent.any, "interrupt controller")
+    system = Param.System(Parent.any, "system")
 
     # for platforms using device trees to set properties of CPU nodes
     def annotateCpuDeviceNode(self, cpu, state):