drm/amdgpu: add missing dpm check for KV dpm late init

Skip dpm late init if dpm is disabled.

Signed-off-by: Alex Deucher <[e-mail]>
Cc: [e-mail]

drivers/gpu/drm/amd/amdgpu/kv_dpm.c

···
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 	int ret;
 
+	if (!amdgpu_dpm)
+		return 0;
+
 	/* init the sysfs and debugfs files late */
 	ret = amdgpu_pm_sysfs_init(adev);
 	if (ret)