kernel flavour rpi-def not available for armh.

This option is required for rpi cores in order for the second monitor
to work. For kernels, std-def and un-def are not required and can lead
to problems on them.

This reverts commit 3e7b8d29.
No need to assign a browser in this feature. This feature used
actually for all aarch64, armh SBC.

Playing FullHD video with YouTube on Raspberry PI 4 in Firefox-ESR
starting with version 91 occurs with strong delays.
https://bugzilla.altlinux.org/41486
In the chromium problem is not observed.

At the moment rpi-def is LTS 5.10 rpi-un is 5.12
Revert "arm-rpi4: Use rpi-un kernel by default"

This reverts commit 857bf72c.

use/arm-rpi4 is now used to improve Raspberry Pi support in
universal rootfs with u-boot.

Fix framebuffer in kernel rpi-un 5.10.20-alt1.

Fixes audio on mainline kernel.
See-also: https://forum.manjaro.org/t/rpi4-a-v-jack-missing-when-using-vc4-driver-kms/50948/19

Not needed more.

framebuffer not working with dtoverlay=vc4-fkms-v3d on RPi3 aarch64.

The Raspberry Pi 4 has hardware acceleration, there is no need to
use special programs.
bluetooth is needed only on a desktop.

While this argument can only have one "EFI" value.
Thus, the problem of building an image for Raspberry Pi on armh,
where there is no grub-efi, was solved.

This is need to working bluetooth with GUI

If there is no Ethernet connection, RPi4 loading stops for 2 minutes.

On Raspberry Pi 3 B Plus with kernel 5.6.16-rpi-un-alt1 occurs
framebuffer error with dtoverlay=vc4-kms-v3d (antohami@)

Changed audio scheduling from timer-based to
interrupt-driven to prevent unwanted crackle.

- Return 0 at the end of the script

uboot.env was breaking u-boot boot on Raspberry Pi 3 because of this.

Also added download support on the Raspberry Pi 3.
The following feature has appeared. The FAT partition does not
install the last installed kernel, but the first kernel in the
KFLAVOURS list. This was done in order to enable  u-boot to
default load another kernel, for example std-def.