gem5: fix fs_bigLITTLE: error: unrecognized arguments: --num-cpus 1

run

@@ -488,6 +488,7 @@ Extra options to append at the end of the emulator command line.
                         extra_emulator_args.extend(['-r', str(cpt_dirs_sorted_by_tick.index(cpt_dir) + 1)])
                     cmd.extend([
                         self.env['gem5_fs_file'], LF,
+                        '--num-cpus', str(self.env['cpus']), LF,
                         '--disk-image', self.env['disk_image'], LF,
                         '--kernel', self.env['image'], LF,
                         '--mem-size', memory, LF,
@@ -573,7 +574,6 @@ Extra options to append at the end of the emulator command line.
             if self.env['gdb_wait']:
                 # https://stackoverflow.com/questions/49296092/how-to-make-gem5-wait-for-gdb-to-connect-to-reliably-break-at-start-kernel-of-th
                 cmd.extend(['--param', 'system.cpu[0].wait_for_remote_gdb = True', LF])
-            cmd.extend(['--num-cpus', str(self.env['cpus']), LF])
         elif self.env['emulator'] == 'qemu':
             qemu_user_and_system_options = [
                 '-trace', 'enable={},file={}'.format(trace_type, self.env['qemu_trace_file']), LF,