test: dfu: cosmetic: Add missing license information to DFU test scripts

By mistake I've forgotten to add the SPDX license tags for the DFU testing
scripts.
This commit fixes that and also provides some other relevant information.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
2 files changed