mkinitcpio / linux-aarch64: remove default fallback preset

[Silhouette]

When upgrading my system on my raspberry pis with 1GB of RAM, I recently started having the issue of mkinitcpio taking a large amount of memory, leading to an OOM situation that makes my machines unreachable for hours. This happens when generating the fallback image, and this is why I want to disable it.

The problem is that the /etc/mkinitcpio.d/linux-aarch64.preset file is automatically overridden on every linux-aarch64 package upgrade (without creating a .pacnew file), and mkinitcpio is called again immediately. This means I can't simply edit the file.

I am thus requesting to remove fallback in the linux-aarch64 preset file (owned by the linux-aarch64 package).

Note that [url=https://github.com/archlinux/mkinitcpio/blob/master/CHANGELOG#L180]mkinitcpio disabled the default fallback preset for the default kernel in v40[/url]. The change I'm requesting is to align with this.