staging: ft1000-usb: use usleep_range instead of msleep

This fixes the following checkpatch.pl warning:
WARNING : msleep < 20ms can sleep for up to 20ms; see
Documentation/timers/timers-howto.txt
Signed-off-by: Catalina Mocanu <catalina.mocanu@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/ft1000/ft1000-usb/ft1000_usb.c

@@ -41,7 +41,7 @@ static int ft1000_poll_thread(void *arg)
 	int ret;
 
 	while (!kthread_should_stop()) {
-		msleep(10);
+		usleep_range(10000, 11000);
 		if (!gPollingfailed) {
 			ret = ft1000_poll(arg);
 			if (ret != 0) {