rcutorture: Don't specify the cpu type of QEMU on PPC

Do not restrict the cpu type to POWER7 for QEMU as we have POWER8 now.
Signed-off-by: NBoqun Feng <boqun.feng@gmail.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>

tools/testing/selftests/rcutorture/bin/functions.sh

@@ -174,7 +174,7 @@ identify_qemu_args () {
 		echo -soundhw pcspk
 		;;
 	qemu-system-ppc64)
-		echo -enable-kvm -M pseries -cpu POWER7 -nodefaults
+		echo -enable-kvm -M pseries -nodefaults
 		echo -device spapr-vscsi
 		if test -n "$TORTURE_QEMU_INTERACTIVE" -a -n "$TORTURE_QEMU_MAC"
 		then