selftests/perf_events: Fix spelling mistake "sycnhronize" -> "synchronize"

There is a spelling mistake in an error message. Fix it.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Colin Ian King <[e-mail]>
Acked-by: Kyle Huey <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/perf_events/watermark_signal.c

···
 	if (waitpid(child, &child_status, WSTOPPED) != child ||
 	    !(WIFSTOPPED(child_status) && WSTOPSIG(child_status) == SIGSTOP)) {
 		fprintf(stderr,
-			"failed to sycnhronize with child errno=%d status=%x\n",
+			"failed to synchronize with child errno=%d status=%x\n",
 			errno,
 			child_status);
 		goto cleanup;