package: remove scripts listed in <pkg>_CONFIG_SCRIPTS from target

The <foo>-config scripts are useless on the target, since they are
only needed for development, so we remove them automatically.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Acked-by: "Samuel Martin" <s.martin49@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>