net: dsa: b53: Print err message on SW_RST timeout

This allows us to differentiate between the possible failure modes of
b53_switch_reset() by looking at the dmesg output.
Signed-off-by: NPaul Barker <pbarker@konsulko.com>
Acked-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/dsa/b53/b53_common.c

@@ -765,8 +765,11 @@ static int b53_switch_reset(struct b53_device *dev)
 			usleep_range(1000, 2000);
 		} while (timeout-- > 0);
 
-		if (timeout == 0)
+		if (timeout == 0) {
+			dev_err(dev->dev,
+				"Timeout waiting for SW_RST to clear!\n");
 			return -ETIMEDOUT;
+		}
 	}
 
 	b53_read8(dev, B53_CTRL_PAGE, B53_SWITCH_MODE, &mgmt);