drm/amd/pm: use attr_update if the attr has it

use attr_update if its available as part of the attribute.
default_attr_update was used even if attr->attr_update is true.
Signed-off-by: Sathishkumar S <sathishkumar.sundararaju@amd.com>
Reviewed-by: Shashank Sharma <Shashank.sharma@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1942,7 +1942,7 @@ static int amdgpu_device_attr_create(struct amdgpu_device *adev,
 
 	BUG_ON(!attr);
 
-	attr_update = attr->attr_update ? attr_update : default_attr_update;
+	attr_update = attr->attr_update ? attr->attr_update : default_attr_update;
 
 	ret = attr_update(adev, attr, mask, &attr_states);
 	if (ret) {