When adding CPU usability blockers I forgot to properly free them when
in virDomainCapsCPUModelsDispose.
Reported-by: NMarc Hartmayer <mhartmay@linux.vnet.ibm.com>
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>
Reviewed-by: NPavel Hrdina <phrdina@redhat.com>