CIFS: Always reset read error to -EIO if no response

Currently we skip setting a read error to -EIO if a stored
result is -ENODATA and a response hasn't been received. With
the recent changes in read error processing there shouldn't be
cases when -ENODATA is set without a response from the server,
so reset the error to -EIO unconditionally.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>