net: mvpp2: fix memory leak in mvpp2_rx

Release skb memory in mvpp2_rx() if mvpp2_rx_refill routine fails

Fixes: b5015854 ("net: mvpp2: fix refilling BM pools in RX path")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Acked-by: Matteo Croce <mcroce@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>