purism-librem5: enable nonfree fw loading for wifi/bt

This is ultimately a workaround for https://source.puri.sm/Librem5/linux-next/-/issues/290

By loading the fw from rootfs, any corrupt fw on the card is ignored and wifi Just Works again. This does break the FSF certification stuff, but pmOS isn't trying for that anyhow. FW is installed with a nonfree package, so folks can opt out of it in pmb init

This MR also includes a kernel version bump, I thought it was good to throw it in since it includes a minor fix for the tps6598x