gpu: nvgpu: add support for voltage config

- changes to read voltage tables from VBIOS
  & create boardobj then send to pmu
- Rail, Device & Policy objects are read from VBIOS & created boardobjs
- RPC support to load, Set & get voltage.

JIRA DNVGPU-122

Change-Id: I61621a514eef9c081a64c4ab066f01dfc28f8402
Signed-off-by: Mahantesh Kumbar <mkumbar@nvidia.com>
Reviewed-on: http://git-master/r/1222774
(cherry picked from commit 9da86d8c2c547623cf5f38c89afeb3f5bb1667ac)
Reviewed-on: http://git-master/r/1244656
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

drivers/gpu/nvgpu/volt/volt.h

@@ -0,0 +1,30 @@
+/*
+* Copyright (c) 2016, NVIDIA CORPORATION.  All rights reserved.
+*
+* This program is free software; you can redistribute it and/or modify it
+* under the terms and conditions of the GNU General Public License,
+* version 2, as published by the Free Software Foundation.
+*
+* This program is distributed in the hope it will be useful, but WITHOUT
+* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+* more details.
+*/
+
+#ifndef _VOLT_H_
+#define _VOLT_H_
+
+#include "volt_rail.h"
+#include "volt_dev.h"
+#include "volt_policy.h"
+#include "volt_pmu.h"
+
+#define VOLTAGE_DESCRIPTOR_TABLE_ENTRY_INVALID	0xFF
+
+struct obj_volt {
+	struct voltage_rail_metadata volt_rail_metadata;
+	struct voltage_device_metadata volt_dev_metadata;
+	struct voltage_policy_metadata volt_policy_metadata;
+};
+
+#endif /* DRIVERS_GPU_NVGPU_VOLT_VOLT_H_ */