net: macb: remove extraneous return when MACB_EXT_DESC is defined

When macro MACB_EXT_DESC is defined we end up with two identical
return statements and just one is sufficient. Remove the extra
return.

Detected by CoverityScan, CID#1449361 ("Structurally dead code")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 41e5711..e69ebdd 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -146,7 +146,6 @@
 	default:
 		break;
 	}
-	return desc_idx;
 #endif
 	return desc_idx;
 }