Linux kernel RNG enhancements for 5.19

If MGLRU is merged, 5.19 will be a landmark as probably one of the most improved kernels in history.

The submitter is Jason Donenfeld, aka zx2c4, creator of Wireguard (and the `pass` password manager). This is an impressive record.

I don't like it when people touch the RNG and I think Wireguard glows.