Long boot times of Zarhus OS

[m-iwanicki]

Default build of Zarhus OS takes quite a long time to boot. Tested on QEMU, raspberrypi 3, Radxa CM3 IO and custom board on each of those booting takes 14-20 seconds with most of that time taken in userspace.

Quick check:

• U-Boot - 6 seconds - with 2 of those being wait for user input
• kernel - about 2-3 seconds
• userspace - rest of time

I think it would be good idea to optimize boot time of Zarhus OS, especially if we want to use it as a base for other distributions.

[pietrushnic]

@m-iwanicki definitely, we should evaluate this effort. How much it would cost and allocate resources internally.