net-next/hinic: fix comparison of a uint16_t type with -1

Remove the search for index of constant buffer size

Signed-off-by: Aviad Krawczyk <aviad.krawczyk@huawei.com>
Signed-off-by: Zhao Chen <zhaochen6@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>