IB/usnic: Fix out of bounds index check in query pkey

mainline inclusion
from mainline-5.0
commit 4959d5da
category: bugfix
bugzilla: 12207
CVE: NA

-------------------------------------------------

The pkey table size is one element, index should be tested for > 0 instead
of > 1.

Fixes: e3cf00d0 ("IB/usnic: Add Cisco VIC low-level hardware driver")
Signed-off-by: Gal Pressman <galpress@amazon.com>
Acked-by: Parvi Kaustubhi <pkaustub@cisco.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
Reviewed-by: Wenan Mao <maowenan@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>