nvidia-gpu: add voltage sensor

This commit introduces a voltage sensor for the GPU.

Tested: Build an image for gb200nvl-obmc machine with the following
patches cherry picked. This patches are needed to enable the mctp stack.

https://gerrit.openbmc.org/c/openbmc/openbmc/+/79422

```
$ curl -s -k -u 'root:0penBmc' https://10.137.203.137/redfish/v1/Chassis/NVIDIA_GB200_1/Sensors/voltage_NVIDIA_GB200_GPU_0_Voltage_0
{
  "@odata.id": "/redfish/v1/Chassis/NVIDIA_GB200_1/Sensors/voltage_NVIDIA_GB200_GPU_0_Voltage_0",
  "@odata.type": "#Sensor.v1_2_0.Sensor",
  "Id": "voltage_NVIDIA_GB200_GPU_0_Voltage_0",
  "Name": "NVIDIA GB200 GPU 0 Voltage 0",
  "Reading": 0.735,
  "ReadingRangeMax": 1.8446744073709552e+16,
  "ReadingRangeMin": 0.0,
  "ReadingType": "Voltage",
  "ReadingUnits": "V",
  "Status": {
    "Health": "OK",
    "State": "Enabled"
  }
}%
```

Change-Id: I3d98f3d7c11221a42460c6f8420c927c1b1711b2
Signed-off-by: Harshit Aghera <haghera@nvidia.com>
diff --git a/src/nvidia-gpu/meson.build b/src/nvidia-gpu/meson.build
index 11aaab3..39ce871 100644
--- a/src/nvidia-gpu/meson.build
+++ b/src/nvidia-gpu/meson.build
@@ -8,6 +8,7 @@
     'NvidiaGpuSensor.cpp',
     'NvidiaGpuSensorMain.cpp',
     'NvidiaGpuThresholds.cpp',
+    'NvidiaGpuVoltageSensor.cpp',
     'OcpMctpVdm.cpp',
 )