ACPI / device_sysfs: Add sysfs support for _HRV hardware revision

The ACPI _HRV object on the device is used to supply Linux with the
device's hardware revision. This is an optional object. Add sysfs support
for the _HRV object if it exists on the device.

This change allows users to easily find the hardware version of non-PCI
hardware by looking at the sysfs 'hrv' file. It is most useful for
non-PCI devices because lspci can list the hardware version for PCI
devices.

Signed-off-by: Betty Dall <betty.dall@hpe.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>