sfc: Remove some unreachable error paths

Some functions return an error code which is always 0.  Change their
return types to void and simplify their callers accordingly.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/net/sfc/efx.h b/drivers/net/sfc/efx.h
index 29a1c58..9a8c283 100644
--- a/drivers/net/sfc/efx.h
+++ b/drivers/net/sfc/efx.h
@@ -33,7 +33,7 @@
 
 /* Channels */
 extern void efx_process_channel_now(struct efx_channel *channel);
-extern int efx_flush_queues(struct efx_nic *efx);
+extern void efx_flush_queues(struct efx_nic *efx);
 
 /* Ports */
 extern void efx_reconfigure_port(struct efx_nic *efx);