net: axienet: remove stale comment of axienet_open

axienet_open no longer return -ENODEV when PHY cannot be connected to
since commit d7cc3163e026 ("net: axienet: Support phy-less mode of operation")

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

@@ -900,7 +900,6 @@ static void axienet_dma_err_handler(unsigned long data);
  * @ndev:	Pointer to net_device structure
  *
  * Return: 0, on success.
- *	    -ENODEV, if PHY cannot be connected to
  *	    non-zero error value on failure
  *
  * This is the driver open routine. It calls phy_start to start the PHY device.