net: Initialize return value in gro_cells_receive

[Gregory Rose]

The 'res' return value is uninitalized and may be returned with
some random value.  Initialize to NET_RX_DROP as the default
return value.
Signed-off-by: Greg Rose <gvrose8...@gmail.com>

diff --git a/net/core/gro_cells.c b/net/core/gro_cells.c
index e095fb871d91..4e835960db07 100644
--- a/net/core/gro_cells.c
+++ b/net/core/gro_cells.c
@@ -13,7 +13,7 @@ int gro_cells_receive(struct gro_cells *gcells, struct 
sk_buff *skb)
 {
        struct net_device *dev = skb->dev;
        struct gro_cell *cell;
-       int res;
+       int res = NET_RX_DROP;

        rcu_read_lock();
        if (unlikely(!(dev->flags & IFF_UP)))