Bug 24745: (follow-up) Correct return statement in news plugin

Subroutine should "return;" instead of "return 0;"
We also prevent ProhibitExplicitReturnUndef by not returning "undef"
explicitly.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

Koha/Template/Plugin/KohaNews.pm

@@ -52,7 +52,7 @@ sub get {
             blocktitle => $blocktitle
         };
     } else {
-        return 0;
+        return;
     }
 }
 
@@ -79,4 +79,4 @@ the following TT code: [% KohaNews.get() %]
 
 Owen Leonard <oleonard@myacpl.org>
 
-=cut
+=cut