lspci: Show device name as exported by BIOS (sysfs label attribute) (V2)

lspci: Show device name as exported by BIOS (sysfs label attribute) (V2)

The Device name of a PCI or PCI Express device under OS may be exported via
ACPI _DSM function with function index 7.
This allows to connect a described PCI device in the platform documentation
or as labeled on the chassis with PCI devices shown via lspci.
The kernel already exports this string through sysfs under a PCI device through
the "label" sysfs attribute.

This patch reads the device name if available and shows it to the user.
Real world examples:
  Device Name: "USB HS EHCI Controller #2 #3"
  Device Name: "USB HS EHCI Controller #1"
  Device Name: "SATA Controller #1"
  Device Name: "Onboard LAN #1"
  Device Name: "Onboard LAN #2"
  Device Name: "Onboard Video (PILOT-3)"

Compare with PCI Firmware Spec v3.1 chapter 4.6.7 and
ACPI spec v5.0 chapter 9.14.1

The DeviceName is not shown by default, but starting from first verbose
parameter (-v).

V2: - Free label string if allocated
    - Enhance changelog

Signed-off-by: Thomas Renninger <trenn@suse.de>
CC: linux-pci@vger.kernel.org