net: ethernet: ti: davinci_cpdma: don't stop ctlr if it was stopped

No need to stop ctlr if it was already stopped. It can cause timeout
warns. Steps:
- ifconfig eth0 down
- ethtool -l eth0 rx 8 tx 8
- ethtool -l eth0 rx 1 tx 1

Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/davinci_cpdma.c

@@ -387,7 +387,7 @@ int cpdma_ctlr_stop(struct cpdma_ctlr *ctlr)
 	int i;
 
 	spin_lock_irqsave(&ctlr->lock, flags);
-	if (ctlr->state == CPDMA_STATE_TEARDOWN) {
+	if (ctlr->state != CPDMA_STATE_ACTIVE) {
 		spin_unlock_irqrestore(&ctlr->lock, flags);
 		return -EINVAL;
 	}