i2c-vr: isl69269: fix tx buffer copy in program()

The data (e.g. pData[i].data) layout is: [addr, cmd, data0..dataN].
Fixed to copy from data+1 (skipping addr) with correct length to
properly format the I2C transmission buffer.

Tested:
```
1. Check firmware info: (current version 5FFB1D09)
~$ curl -k -u root:0penBmc -X GET https://10.2.230.66/redfish/v1/UpdateService/FirmwareInventory/Catalina_PDB_vr_n1_8217
{
  "@odata.id": "/redfish/v1/UpdateService/FirmwareInventory/Catalina_PDB_vr_n1_8217",
  "@odata.type": "#SoftwareInventory.v1_1_0.SoftwareInventory",
  "Description": "Unknown image",
  "Id": "Catalina_PDB_vr_n1_8217",
  "Name": "Software Inventory",
  "Status": {
    "Health": "OK",
    "HealthRollup": "OK",
    "State": "Enabled"
  },
  "Updateable": true,
  "Version": "5FFB1D09"
}

2. Trigger Update: (update to version C001A89C)
~$ curl -k -u root:0penBmc \
-H "Content-Type:multipart/form-data" \
-X POST \
-F UpdateParameters="{\"Targets\":[\"/redfish/v1/UpdateService/FirmwareInventory/Catalina_PDB_vr_n1_8217\"],\"@Redfish.OperationApplyTime\":\"OnReset\"};type=application/json" \
-F "UpdateFile=@catalina-raa-n1_C001A89C.pldm;type=application/octet-stream" \
https://10.2.230.66/redfish/v1/UpdateService/update-multipart
{
  "@odata.id": "/redfish/v1/TaskService/Tasks/0",
  "@odata.type": "#Task.v1_4_3.Task",
  "HidePayload": false,
  "Id": "0",
  "Messages": [
    {
      "@odata.type": "#Message.v1_1_1.Message",
      "Message": "The task with Id '0' has started.",
      "MessageArgs": [
        "0"
      ],
      "MessageId": "TaskEvent.1.0.TaskStarted",
      "MessageSeverity": "OK",
      "Resolution": "None."
    }
  ],
  "Name": "Task 0",
  "Payload": {
    "HttpHeaders": [],
    "HttpOperation": "POST",
    "TargetUri": "/redfish/v1/UpdateService/update-multipart"
  },
  "PercentComplete": 0,
  "StartTime": "2025-09-17T17:15:50+00:00",
  "TaskMonitor": "/redfish/v1/TaskService/TaskMonitors/0",
  "TaskState": "Running",
  "TaskStatus": "OK"
}

3. After AC cycle check firmware info again:
~$ curl -k -u root:0penBmc -X GET https://10.2.230.66/redfish/v1/UpdateService/FirmwareInventory/Catalina_PDB_vr_n1_332
{
  "@odata.id": "/redfish/v1/UpdateService/FirmwareInventory/Catalina_PDB_vr_n1_332",
  "@odata.type": "#SoftwareInventory.v1_1_0.SoftwareInventory",
  "Description": "Unknown image",
  "Id": "Catalina_PDB_vr_n1_332",
  "Name": "Software Inventory",
  "Status": {
    "Health": "OK",
    "HealthRollup": "OK",
    "State": "Enabled"
  },
  "Updateable": true,
  "Version": "C001A89C"
}
```

Change-Id: I454ad86c2aaa74f675cd5c753a37603bc3e55448
Signed-off-by: Cosmo Chou <cosmo.chou@quantatw.com>
diff --git a/i2c-vr/isl69269/isl69269.cpp b/i2c-vr/isl69269/isl69269.cpp
index 42fb925..399a80f 100644
--- a/i2c-vr/isl69269/isl69269.cpp
+++ b/i2c-vr/isl69269/isl69269.cpp
@@ -390,9 +390,8 @@
 
     for (int i = 0; i < configuration.wrCnt; i++)
     {
-        tbuf[0] = configuration.pData[i].cmd;
-        std::memcpy(tbuf + 1, &configuration.pData[i].data,
-                    configuration.pData[i].len - 1);
+        std::memcpy(tbuf, configuration.pData[i].data + 1,
+                    configuration.pData[i].len);
 
         if (!(co_await i2cInterface.sendReceive(
                 tbuf, configuration.pData[i].len, rbuf, rlen)))