PCI/sysfs: Ensure devices are powered for config reads (part 2)

Commit 48991e49 ("PCI/sysfs: Ensure devices are powered for config
reads") was applied to various linux-stable trees. However, prior to
6.12.y, we do not have commit d2bd39c0 ("PCI: Store all PCIe
Supported Link Speeds"). Therefore, we also need to apply the change to
max_link_speed_show().

This was pointed out here:

  Re: Patch "PCI/sysfs: Ensure devices are powered for config reads" has been added to the 6.6-stable tree
  https://lore.kernel.org/all/aPEMIreBYZ7yk3cm@google.com/

Original change description follows:

    The "max_link_width", "current_link_speed", "current_link_width",
    "secondary_bus_number", and "subordinate_bus_number" sysfs files all access
    config registers, but they don't check the runtime PM state. If the device
    is in D3cold or a parent bridge is suspended, we may see -EINVAL, bogus
    values, or worse, depending on implementation details.

    Wrap these access in pci_config_pm_runtime_{get,put}() like most of the
    rest of the similar sysfs attributes.

    Notably, "max_link_speed" does not access config registers; it returns a
    cached value since d2bd39c0 ("PCI: Store all PCIe Supported Link
    Speeds").

Fixes: 56c1af46 ("PCI: Add sysfs max_link_speed/width, current_link_speed/width, etc")
Link: https://lore.kernel.org/all/aPEMIreBYZ7yk3cm@google.com/


Signed-off-by: Brian Norris <briannorris@google.com>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>