Add dependencies for dm-verity and some dm-crypt

[lawik]

This change adds the crypto parts required by dm-verity (and some of dm-crypt) to the kernel, compiled in.

This includes various algorithms (mainly SHA256/512 and CRC32C) but also the device mapper and more related pieces.

[lawik]

Happy to trim back and try again if you know things that shouldn't be necessary. I tried to both be restrictive and select what I believe I'll need for dm-verity and shortly dm-crypt.

[lawik]

Oh, btw I'm not assuming this should live in nerves_system_rpi4. If need be it is a separate system. But figured I'd PR since I'd done the effort.

[fhunleth]

My feeling is that if there's an open source way of using all of this that we should definitely include here.

[lawik]

Yeah, this PR could hang out for a bit until I have wrapped up the library and the related initramfs so that the end-to-end tooling and documentation is fully there. Would definitely be awesome to have this in the system by default as far as I'm concerned.

I was mostly concerned with the swelling. So no worries if it becomes too much. It is not kiosk-level big but I don't know what yardstick we use to measure what goes in and not :)

[lawik]

This seems to be all I need for dm-verity and dm-crypt.

This should keep me from needing to run a custom system to get a CM4 Secure Boot setup and all that going. Lots of fun over in the initramfs and library side as well as some customization of the specific project. But I'll try to package that up nicely on the library end.