tty/max3100: don't use [delayed_]work_pending()

There's no need to test whether a (delayed) work item in pending
before queueing, flushing or cancelling it.  Most uses are unnecessary
and quite a few of them are buggy.

Remove unnecessary pending tests from max3100.  Only compile tested.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>

drivers/tty/serial/max3100.c

@@ -179,8 +179,7 @@ static void max3100_work(struct work_struct *w);
 
 static void max3100_dowork(struct max3100_port *s)
 {
-	if (!s->force_end_work && !work_pending(&s->work) &&
-	    !freezing(current) && !s->suspending)
+	if (!s->force_end_work && !freezing(current) && !s->suspending)
 		queue_work(s->workqueue, &s->work);
 }