LGTM.com - false positive - Wrong name for an argument in a call

**Description of the false positive**

> Keyword argument 'colname' is not a supported parameter name of [method WcsMap.from_hdulist](https://lgtm.com/projects/g/gammapy/gammapy/snapshot/5ca2435aeda0464818072e3851e74667e47eb032/files/gammapy/maps/wcs/core.py?sort=name&dir=ASC&mode=heatmap#xaf02554c80eb082b:1).

Indeed, method `WcsMap.from_hdulist()` does not have support `colname` as a keyword argument, but in this case [`cls_out`is a not a `WcsMap` but an `HpxGeom`](https://github.com/gammapy/gammapy/blob/c93a4a9/gammapy/maps/core.py#L264-L268):
```python
cls_out = Map._get_map_cls(map_type)
if map_type == "hpx":
return cls_out.from_hdulist(
hdulist, hdu=hdu, hdu_bands=hdu_bands, format=format, colname=colname
)
```

**URL to the alert on the project page on LGTM.com**

https://lgtm.com/projects/g/gammapy/gammapy/snapshot/5ca2435aeda0464818072e3851e74667e47eb032/files/gammapy/maps/core.py?sort=name&dir=ASC&mode=heatmap#xa96f69c1f157a42e:1