metadata.pl: fixpath exclusion of kernel packages

module and build deps did not work for kernel modules

Signed-off-by: John Crispin <blogic@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@37091 3c298f89-4303-0410-b956-a3cf2f4a3e73