85-initrd: fix the args number

`kernel-install` pass 5 args to modules anyway, so empty argument
do not allow to install the initrd file into boot entry directory.
Since we do not pass the initrd name via options module
`90-loaderentry.install` also skip the initrd copying and setup.

Signed-off-by: Denis Pynkin <denis.pynkin@collabora.com>