Deprecate install/archiso_kms since the hook was moved to the mkinitcpio project
This hook is now part of mkinitcpio and is called "kms". Place a symlink leading to the new name so that "archiso_kms" still keeps working while showing the "This hook is deprecated" message.
See https://github.com/archlinux/mkinitcpio/issues/94 and https://github.com/archlinux/mkinitcpio/pull/95