C4 - upgrade ubuntu in place

[skimenlo]

I am running Ubuntu 20 [4.9.218] on multiple C4's.
I want to enable I2S audio on them. This seems to require editing the device tree overlay at /media/boot/config.ini.

The I2S instructions at https://wiki.odroid.com/accessory/sound ... _odroid-c4 say
"Kernel version should be 4.9.230 or higher version."

The recent Ubuntu C4 image on Hardkernel Downloads is 4.9.277.
How can I update my C4's to [say] 4.9.277 (or other greater than 4.9.230)?