selftests: timers: clocksource-switch: adapt to kselftest framework

So we have proper counters at the end of a test. We also print the
kselftest header at the end of the test, so we don't mix with the output
of the child process. There is only this one test anyhow.

Signed-off-by: Wolfram Sang <[e-mail]>
Acked-by: John Stultz <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/timers/clocksource-switch.c

···
 out:
 	change_clocksource(orig_clk);
 
-	if (status)
-		return ksft_exit_fail();
-	return ksft_exit_pass();
+	/* Print at the end to not mix output with child process */
+	ksft_print_header();
+	ksft_set_plan(1);
+	ksft_test_result(!status, "clocksource-switch\n");
+	ksft_exit(!status);
 }