net_open previously casted the first vararg to a char * and this was half-OK: at first, it is passed to netif_open, which would cast it back to the struct devdesc * that it really is and use it properly. It is then strdup()d and used as the netdev_name, which is objectively wrong.

Correct it so that the first vararg is properly casted to a struct devdesc * and the netdev_name gets set properly to make it more clear at a glance that it's not doing something horribly wrong.

Reported by: mmel

I have a separate patch that const poisons machdep_hint in libsa/netif from before the realization hit me that netif_open really shouldn't be passed a string. I don't know if we care enough to do this, but I tend to think it wouldn't hurt as none of these things really do (or should) modify the hint.