storage: Fix building

After *.ycp files from src/include/partitioning were removed in
3bd0050977e7086d41137d0d241d79f813c7250d, rpmbuild started to complain
about a glob in specfile that didn't match any files and refused to
build. This commit fixes that.
Merge pull request #436 from yast/fix-storage-build

storage: Fix building