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/perf/perf.h

@@ -17,6 +17,7 @@
 #include "vfe_var.h"
 #include "pstate/pstate.h"
 #include "gk20a/gk20a.h"
+#include "volt/volt.h"
 
 #define CTRL_PERF_VFE_VAR_TYPE_INVALID                               0x00
 #define CTRL_PERF_VFE_VAR_TYPE_DERIVED                               0x01
@@ -55,6 +56,7 @@ struct perf_pmupstate {
 	struct vfe_vars vfe_varobjs;
 	struct vfe_equs vfe_equobjs;
 	struct pstates pstatesobjs;
+	struct obj_volt volt;
 };
 
 u32 perf_pmu_vfe_load(struct gk20a *g);