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.

This trigger file will delete all lines containing fdtdir after
installing a new kernel version.

- Return 0 at the end of the script

When loading u-boot + extlinux.conf, needs specific arguments that
are not needed when using grub-efi

See-also: c0c5c94b