RDMA/ipoib: Fix check for return code from ib_create_srq

Make sure to check for "-EOPNOTSUPP" instead of "-ENOSYS" which is the
return code from ib_create_srq() in case that it not supported.

Signed-off-by: Kamal Heib <kamalheib1@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>