Update to mkinitcpio runing microcode hook
https://bbs.archlinux.org/viewtopic.php?id=293834


grub-mkconfig can find ucodes itself and has a predefined list:

GRUB_EARLY_INITRD_LINUX_STOCK="intel-uc.img intel-ucode.img amd-uc.img amd-ucode.img early_ucode.cpio microcode.cpio"

Add
GRUB_EARLY_INITRD_LINUX_STOCK=""

Ok, made the changes and run mkinicpio and grub-mkconfig.. rebooted, amd-ucode.img is no longer in initrd [grub]