mainline inclusion
from mainline-v5.7-rc1
commit e56faff5
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I47H3V
CVE: NA

--------------------------------

Add pci_speed_string() to return a text description of the supplied bus or
link speed.  The slot code previously used the private
pci_bus_speed_strings[] array for this purpose, but adding this interface
will enable us to consolidate similar code elsewhere.

Export pcie_link_speed[] and pci_speed_string() so they can be used by
modules.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Nliyouhong <liyouhong@kylinos.cn>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NXiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>