There is an SoC bug of v3 hw development version. When hot- unplugging a
directly attached disk, the PHY down interrupt may not happen. It is
very easy to appear on some boards.

When this issue occurs, the controller will receive many invalid dword
frames, and the "alos" fields of register HILINK_ERR_DFX can indicate
that disk was unplugged.

As an workaround solution, this patch detects this issue in the channel
interrupt, and workaround it by following steps:

 - Disable the PHY
 - Clear error code and interrupt
 - Enable the PHY

Then the HW will reissue PHY down interrupt.
Signed-off-by: Xiaofei Tan <tanxiaofei@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>