ovirt-disk: Fix content type property name
    
    Instead of using underscore, which is not accepted, make use of a dash,
    avoiding error messages like the following:
    
    GLib-CRITICAL **: g_param_spec_internal: assertion '!(flags & G_PARAM_STATIC_NAME) || is_canonical (name)' failed
    
    Signed-off-by: Eduardo Lima (Etrunko) <etrunko@redhat.com>
    
    patch_name: 0003-ovirt-disk-Fix-content-type-property-name.patch
    present_in_specfile: true
    location_in_specfile: 3
    squash_commits: true