drm/amdgpu/pm: update hwmon power documentation

Power reporting is socket power.  On APUs this includes
the CPU.  Update the documentation to clarify this.
Reviewed-by: Aaron Liu <aaron.liu@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/amdgpu_pm.c

@@ -3059,7 +3059,7 @@ static ssize_t amdgpu_hwmon_show_mclk_label(struct device *dev,
  *
  * hwmon interfaces for GPU power:
  *
- * - power1_average: average power used by the GPU in microWatts
+ * - power1_average: average power used by the SoC in microWatts.  On APUs this includes the CPU.
  *
  * - power1_cap_min: minimum cap supported in microWatts
  *