arch: Delete authors lists from the null arch files.

Change-Id: Ief42708d8961a5c33db5e8a603ee8fff8df8b198
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/25446
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/null/SConscript

@@ -34,8 +34,6 @@
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-#
-# Authors: Andreas Hansson
 
 Import('*')