xprtrdma: Make sure Send CQ is allocated on an existing compvec

mainline inclusion
from mainline-v5.0-rc7
commit a4cb5bdb
category: bugfix
bugzilla: 10737
CVE: NA

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

Make sure the device has at least 2 completion vectors
before allocating to compvec#1

Fixes: a4699f56 (xprtrdma: Put Send CQ in IB_POLL_WORKQUEUE mode)
Signed-off-by: Nicolas Morey-Chaisemartin <nmoreychaisemartin@suse.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Lin Miaohe <linmiaohe@huawei.com>
Reviewed-by: Mao Wenan <maowenan@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>