Add methods to retrieve physical device information

[dhduvall]

This is functionality I need for my work, but it needs some checking. I'm happy to rename and re-type things. There's one XXX comment that should probably be addressed. There's also plenty of PHY-related stuff that I didn't add because I didn't need it and I didn't want to go too far down the rabbit-hole until I knew I was going down the right one.

[mdlayher]

Thanks for the PR. I'm a bit busy at work this week but I'll try to get to this if I have some free time in the next couple of days.

[dhduvall]

One thing I'm unsure about (and more so now that I'm looking at adding the VHT bits) is whether the A-MPDU members I stuck in BandAttributes really belong there instead of in HTCapabilities. Right now, HTCapabilities is a representation of the 16-bit HT Capabilities structure in the frame (and how precisely the kernel relates that to the configuration-like bits that we get in userland over netlink, I don't know, and I never got a response to that from the linux-wireless list), but that's somewhat by accident, because I created the structs to match the netlink attribute structure, which may not be the best thing to follow. AFAICT, those A-MPDU members are really HT-specific; there are similar ones for VHT, but rather than being communicated over netlink as separate attributes, they're just bits in the VHT Capabilities bitset.

I'd be okay with simply pulling them out (or making them private) for now, if that's more comfortable, since I don't need them.

[dhduvall]

I think I'm done twiddling on this. I've also got VHT changes nearly ready to go.

[henrikkorsgaard]

Any status on merging this pull request?

[SuperQ]

This needs a rebase.

[SuperQ]

Closing as stale. Anyone seeing this is welcome to open a new PR with a rebase.