Input: ads7846 - use msleep() instead of udelay() in suspend

Sometimes a polling loop had a hard time changing state without
pre-emption enabled.  Use msleep instead, it's better anyway.
Signed-off-by: Juha Yrjola <juha.yrjola@nokia.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/touchscreen/ads7846.c

@@ -449,7 +449,7 @@ ads7846_suspend(struct spi_device *spi, pm_message_t message)
 
 		while (ts->pendown || ts->pending) {
 			spin_unlock_irqrestore(&ts->lock, flags);
-			udelay(10);
+			msleep(1);
 			spin_lock_irqsave(&ts->lock, flags);
 		}
 	}