Keep the asahi mkinitcpio hook in the aarch64 package (#358)

Upstream omarchy-settings package() deletes /etc/mkinitcpio.conf.d
wholesale on aarch64, reasoning that omarchy_hooks.conf is the x86 file
that would inject the Limine hooks into an Asahi initramfs. That holds
for upstream's copy of the file. It does not hold for ours: this fork
rewrote the same path to insert the asahi hook, which stages the Apple
Silicon display, Wi-Fi and neural-engine firmware into early boot, and
to drop btrfs-overlayfs when limine-snapper-sync is absent.

Nothing put it back, so a package built through that PKGBUILD ships
without the hook. It does not fail at install; it fails at the next
mkinitcpio run, when the initramfs is regenerated without asahi and the
machine wedges in early boot with no keyboard.

This has not shipped because the published packages were built as arch
any, where the CARCH == aarch64 branch never ran. Building them properly
as aarch64 turns it on.

Narrow the deletion to the Limine entry-tool config, the part that
really is x86 only, rather than forking the PKGBUILD. Refuse to build if
upstream restructures that line, since silently not matching would ship
exactly the package this prevents.