cpu: Stop including arch/isa.hh.

This header file is no longer needed.

Also fix some places where the isa header file was being transitively
included.

Change-Id: Ib9a9d7db0c9808b29d7614bbd68e2052ea345e9f
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/51239
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/cpu/minor/dyn_inst.cc

@@ -40,7 +40,6 @@
 #include <iomanip>
 #include <sstream>
 
-#include "arch/isa.hh"
 #include "cpu/base.hh"
 #include "cpu/minor/trace.hh"
 #include "cpu/null_static_inst.hh"

src/cpu/simple_thread.hh

@@ -49,7 +49,6 @@
 #include "arch/generic/mmu.hh"
 #include "arch/generic/pcstate.hh"
 #include "arch/generic/tlb.hh"
-#include "arch/isa.hh"
 #include "base/logging.hh"
 #include "base/types.hh"
 #include "config/the_isa.hh"