configs: Remove simpleSystem factory function

The function had been introduced in the past when we needed to
instantiate either an ArmSystem or a LinuxArmSystem depending on the
workload. Now that the workload object has been introduced in gem5, we
always instantiate an ArmSystem in FS mode, hence we don't need a
function to generate the System object

Change-Id: I79ccf31087b84521cce32da71bc835ff202dc432
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/43285
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

configs/example/arm/starter_fs.py

@@ -96,8 +96,7 @@ def create(args):
     # Only simulate caches when using a timing CPU (e.g., the HPI model)
     want_caches = True if mem_mode == "timing" else False
 
-    system = devices.simpleSystem(ArmSystem,
-                                  want_caches,
+    system = devices.SimpleSystem(want_caches,
                                   args.mem_size,
                                   mem_mode=mem_mode,
                                   workload=ArmFsLinux(