net: hisilicon: Fix potential use-after-free in hix5hd2_rx()

The skb is delivered to napi_gro_receive() which may free it, after
calling this, dereferencing skb may trigger use-after-free.

Fixes: 57c5bc9a

 ("net: hisilicon: add hix5hd2 mac driver")
Signed-off-by: Liu Jian <liujian56@huawei.com>
Link: https://lore.kernel.org/r/20221203094240.1240211-2-liujian56@huawei.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>