This patch implements LED feature of directly attached disk for v2 hw.
As libsas has provided an interface lldd_write_gpio() for this feature,
we just need realise the interface following SPGIO API.

We use an CPLD to finish the hardware part of this feature, and the base
address of CPLD should be configured through ACPI or DT tables.
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>