platform/x86/amd: pmc: Add sysfs files for SMU

The CPU/APU SMU FW version and program is currently discoverable by
turning on dynamic debugging or examining debugfs for the amdgpu
driver. To make this more discoverable, create a dedicated sysfs
file for it that userspace can parse without debugging enabled.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20220914141850.259-1-mario.limonciello@amd.com


Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>