hisi_sas: Add initial bare main driver

This patch adds the initial bare main driver for the HiSilicon SAS
HBA. This only introduces the changes to build and load the main driver
module.

The complete driver consists of the core main module and also a module
platform driver for driving the hw.

The HBA is a platform device.

Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>