drm/amd/powerplay: Fix double unlock bug in smu_sys_set_pp_table()

We already unlocked a few lines earlier so this code unlocks twice on
the success path.

Fixes: 289921b0 ("drm/amd/powerplay: implement sysfs of pp_table for smu11 (v2)")
Reviewed-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Kevin Wang <kevin1.wang@amd.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/powerplay/amdgpu_smu.c

@@ -187,6 +187,8 @@ int smu_sys_set_pp_table(struct smu_context *smu,  void *buf, size_t size)
 	if (ret)
 		pr_info("smu reset failed, ret = %d\n", ret);
 
+	return ret;
+
 failed:
 	mutex_unlock(&smu->mutex);
 	return ret;