configs: Fill in the cpu.isa field in etrace_replay.py since no default are provided now

Change-Id: I5f337b9969820bd74ed67e576e2d1a8e4666ecdb
Reviewed-on: https://gem5-review.googlesource.com/7021
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
diff --git a/configs/example/etrace_replay.py b/configs/example/etrace_replay.py
index 385a2d1..f8586d6 100644
--- a/configs/example/etrace_replay.py
+++ b/configs/example/etrace_replay.py
@@ -104,6 +104,11 @@
 for cpu in system.cpu:
     cpu.clk_domain = system.cpu_clk_domain
 
+# BaseCPU no longer has default values for the BaseCPU.isa
+# createThreads() is needed to fill in the cpu.isa
+for cpu in system.cpu:
+    cpu.createThreads()
+
 # Assign input trace files to the Trace CPU
 system.cpu.instTraceFile=options.inst_trace_file
 system.cpu.dataTraceFile=options.data_trace_file