Use SPDX licence
Convert to SPDX license by https://fedoraproject.org/wiki/Changes/SPDX_Licenses_Phase_2,
$ license-fedora2spdx 'GPLv3'
GPL-3.0-only
Signed-off-by: Tao Liu <ltao@redhat.com>
Acked-by: Kairui Song <ryncsn@gmail.com>
Signed-off-by: Kairui Song <ryncsn@gmail.com>