rtsx_usb_ms: use schedule_timeout_idle() in polling loop

First version of this patch has already been posted to LKML by Ben Hutchings ~6 months ago, but no further action were performed.

Original Ben's message goes below.

===
rtsx_usb_ms creates a task that mostly sleeps, but tasks in uninterruptible sleep still contribute to the load average (for bug-compatibility with Unix). A load average of ~1 on a system that should be idle is somewhat alarming.

Change the sleep to be interruptible, but still ignore signals.
===

v2 of this patch uses schedule_timeout_idle() instead of msleep() and removes flush_signals() introduces in v1 of this patch as kthread ignores all signals unless it does allow_signal().

References: https://bugs.debian.org/765717

---
 drivers/memstick/host/rtsx_usb_ms.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 1105db2..d34bc35 100644
@@ -706,7 +706,7 @@ poll_again:
 		if (host->eject)
 			break;
 
-		msleep(1000);
+		schedule_timeout_idle(HZ);
 	}
 
 	complete(&host->detect_ms_exit);

2.8.2