iquik: Updates.

Update README.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
iquik: fix installer bug

Preboot changes introduced a bug if you didn't pass a preboot script.

Sigh.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
iquik: OpenBIOS-related and distrib cleanups.

Update prebuilts.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>