generic-x86_64: include all Intel GPU fw in the initramfs

Newer Intel GPUs won't work without the GUC fw, and older ones still need DMC fw for power management, so let's just include everything... pkgs.alpinelinux.org says the install size is only 9MB...

Note that this was not added to the oem-intel package because it would make the initramfs too big for some devices that depend on oem-intel (e.g. x64-cros)