devctl_process_running(): Check for devsoftc.inuse == 1 instead of

devsoftc.async_proc != NULL because the latter might not be true
sometimes.
This way /etc/rc.suspend gets executed.

Reviwed	by:	njl
Submitted by:	Mitsuru IWASAKI <iwasaki at jp.FreeBSD.org>
Tested also by:	Andreas Wetzel <mickey242 at gmx.net>
MFC after:	1 week

sys/kern/subr_bus.c

@@ -514,7 +514,7 @@ devpoll(struct cdev *dev, int events, d_thread_t *td)
 boolean_t
 devctl_process_running(void)
 {
-	return (devsoftc.async_proc != NULL);
+	return (devsoftc.inuse == 1);
 }
 
 /**