[ATM]: No need to return void

The module_exit function has return-type void and pci_unregister_driver()
returns void anyway.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/atm/horizon.c b/drivers/atm/horizon.c
index f593492..44268cb 100644
--- a/drivers/atm/horizon.c
+++ b/drivers/atm/horizon.c
@@ -2932,8 +2932,8 @@
 
 static void __exit hrz_module_exit (void) {
   PRINTD (DBG_FLOW, "cleanup_module");
-  
-  return pci_unregister_driver(&hrz_driver);
+
+  pci_unregister_driver(&hrz_driver);
 }
 
 module_init(hrz_module_init);