radeonsi: remove 'Authors:' comments

It's inaccurate. Instead, see the copyright and use "git log" and
"git blame" to know the authorship.

Acked-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

src/gallium/drivers/radeonsi/si_debug.c

@@ -19,9 +19,6 @@
  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  * USE OR OTHER DEALINGS IN THE SOFTWARE.
- *
- * Authors:
- *      Marek Olšák <maraeo@gmail.com>
  */
 
 #include "si_pipe.h"