PCI: kirin: Add MSI support

Add support for MSI to the kirin host controller driver, based
on the generic dwc infrastructure.

Signed-off-by: Xiaowei Song <songxiaowei@hisilicon.com>
Signed-off-by: Yao Chen <chenyao11@huawei.com>
[lorenzo.pieralisi@arm.com: updated commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>