Update versions

[uSpike]

Update the version of snapclient and the kernels for RPi, consistent with buildroot 2021.11

[fuchsmich]

Great! Thank you.

I also had to alter wpa_supplicant config for working wlan (on a rpi3):

-Dwext is deprecated https://github.com/fuchsmich/snapos/blob/a57b0d6dad67a3f994fb70527bcc0d87212317ed/buildroot-external/board/raspberrypi/common/post-build.sh#L16

Also wpa_supplicant complained about the first line in /etc/wpa_supplicant.conf ctrl_interface=/var/run/wpa_supplicant. After removing it, wlan worked like before.

Some more improvement to wlan:

• remove dhcpcd as udhcpc is already running. Now the machine gets two IP adresses from dhcp-server.
• Add this line so the hostname gets submitted to dhcp-server (default behaviour on most machines) by udhcpc

[uSpike]

I can add those improvements (probably tonight), thanks @fuchsmich

[uSpike]

@fuchsmich I've updated with all of your comments except for removing dhcpcd and the hostname addition. These changes aren't related to newer versions of buildroot/linux so I think we should open a separate PR to incorporate those changes.