net: hns3: fix a SSU buffer checking bug

When caculating the SSU buffer, it first allocate tx and
rx private buffer, then the remaining buffer is for rx
shared buffer. The remaining buffer size should be at
least bigger than or equal to the shared_std, which is the
minimum shared buffer size required by the driver, but
currently if the remaining buffer size is equal to the
shared_std, it returns failure, which causes SSU buffer
allocation failure problem.

This patch fixes this problem by rounding up shared_std before
checking the the remaining buffer size bigger than or equal to
the shared_std.

Fixes: 46a3df9f ("net: hns3: Add HNS3 Acceleration Engine & Compatibility Layer Support")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>