infra: remove unused 4th parameter to package infrastructures (pkgparentdir)

The fourth parameter to inner-generic-package is no longer used. Removing
this parameters requires renaming all usages of $(5) to $(4), and updating
the calls to inner-generic-package (and equivalent for the other package
infrastructures).

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>