host-build: always define Host/Prepare/Default

host-build: always define Host/Prepare/Default

We currently skip defining Host/Prepare/Default if HOST_UNPACK is not
defined.

This is mostly the case for Host packages that just provide files with
the src directory and don't need to be downloaded/extracted.

This was probably done lots of times ago due to quilt causing error as
the patches directory wasn't present.
This has changed now and quilt can correctly detect if no patches needs
to be applied (instead of terminating with error)

Always define Host/Prepare/Default to make tools/refresh correctly works
as HOST_QUILT is hardcoded enabled for this make target and will
complain for tool not prepared for quilt patches.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>