[regtool] IP block defines device interfaces, named ['regif'] but its registers don't match (they are keyed by [None])

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### Description

Hello,

I am facing an issue when trying to use the regtool **standalone**.
I have an IP with some simple registers, set the clocking, bus_interfaces, and everything in the hjson, but I am getting an error like this, and I'm stuck now.

`ERROR: IP block reset_controller defines device interfaces, named ['regif'] but its registers don't match (they are keyed by [None]).`

All registers are defined like this:

```
{
name: "IP_VERSION",
desc: "Info register: version, release date, etc.",
swaccess: "ro",
fields: [
//Field definitions
{
name: "PATCH",
desc: "",
bits: "7:0",
swaccess: "ro",
resval: "0"
},
{
name: "MINOR",
desc: "",
bits: "15:8",
swaccess: "ro",
resval: "0"
},
{
name: "MAJOR",
desc: "",
bits: "23:16",
swaccess: "ro",
resval: "1"
}
]
}
```

I've searched the docs and the web for solutions, but couldn't find any.
If someome could help me, It would be much appriciated.

Start with the standalone regtool invocation and the HJSON configuration described in the issue, focusing on the clocking, bus_interfaces, and register definitions. Determine why the device interface is keyed as regif while the registers are keyed as None; done means the configuration is accepted without the reported mismatch error.

Written by the indexing model from the issue text.