drm/tests: helpers: Add module infos

The MODULE_LICENSE macro is missing from the kunit helpers file, thus
leading to a build error.

Let's introduce it along with MODULE_AUTHOR.

Fixes: 44a3928 ("drm/tests: Add Kunit Helpers")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Maíra Canal <mairacanal@riseup.net>
Link: https://lore.kernel.org/r/20221116091712.1309651-2-maxime@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>

drivers/gpu/drm/tests/drm_kunit_helpers.c

@@ -64,3 +64,6 @@ struct drm_device *drm_kunit_device_init(struct kunit *test, u32 features, char
 
 	return drm;
 }
+
+MODULE_AUTHOR("Maxime Ripard <maxime@cerno.tech>");
+MODULE_LICENSE("GPL");