ng-spice-rework: remove package

This package has been marked deprecated in October, and no-one
complained. Moreover, it doesn't sound like a package that is widely
used on embedded systems. So we get rid of it.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>