xhci: hisilicon: support HiSilicon STB xHCI host controller

This commit adds support for HiSilicon STB xHCI host controller.
There are two xHCI host controllers on HiSilicon STB SoCs. Each
one requires additional configuration before exposing interface
compliant with xHCI.

Reviewed-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Jianguo Sun <sunjianguo1@huawei.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>