net: hns3: Fix for rx_priv_buf_alloc not setting rx shared buffer

rx_priv_buf_alloc is used to tell hardware how much buffer is
used for rx direction, right now only the private buffer is
assigned.
For ae_dev that doesn't support DCB, private rx buffer is assigned
to zero, only shared rx buffer is used. So not setting the shared
rx buffer cause dropping of packet in SSU.

Fixes: 46a3df9f ("net: hns3: Add HNS3 Acceleration Engine & Compatibility Layer Support")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>