cpu-hotplug selftests: print failure status instead of cause make error

Original behavior:
  bash-4.1$ make -C cpu-hotplug run_tests
  make: Entering directory `/home/dave/git/linux-2.6/tools/testing/selftests/cpu-hotplug'
  ./on-off-test.sh
  make: execvp: ./on-off-test.sh: Permission denied
  make: *** [run_tests] Error 127
  make: Leaving directory `/home/dave/git/linux-2.6/tools/testing/selftests/cpu-hotplug'

After applying the patch:
  bash-4.1$ make -C cpu-hotplug run_tests
  make: Entering directory `/home/dave/git/linux-2.6/tools/testing/selftests/cpu-hotplug'
  /bin/sh: ./on-off-test.sh: Permission denied
  cpu-hotplug selftests: [FAIL]
  make: Leaving directory `/home/dave/git/linux-2.6/tools/testing/selftests/cpu-hotplug'
Signed-off-by: NDave Young <dyoung@redhat.com>
Reviewed-by: NPekka Enberg <penberg@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

tools/testing/selftests/cpu-hotplug/Makefile

 all:
 
 run_tests:
-	./on-off-test.sh
+	@./on-off-test.sh || echo "cpu-hotplug selftests: [FAIL]"
 
 clean: