Fix ovirt local repo issue if AUTOBUILD_PACKAGE_ROOT is not set

When AUTOBUILD_PACKAGE_ROOT is not set, OVIRT_LOCAL_REPO will be
file:///rpm/RPMS. But in fact, the actual ovirt-node repository is
file:///$HOME/rpmbuild/RPMS/noarch.

Change-Id: I6e6bc4482dfd0e7bc6b1eb483b192cb1d901a753
Signed-off-by: Wenyi Gao <wenyi@linux.vnet.ibm.com>