stage2: fix 10-initrd-base for current make-initrd

It was removing autodetection setting completely
thus implicitly setting it to the default "all"
with make-initrd-0.8.1+; just set it to be empty.

Thanks legion@ and boyarsh@; see also #28578.
0.9.8.1-alt1

- works with make-initrd 0.8.1+ (see #28578)
gear-store-tags