RDMA/hns: Query the number of functions supported by the PF

Query how many functions are supported by the PF from the FW and store it
in the hns_roce_dev structure which will be used to support the
configuration of virtual functions.

Link: https://lore.kernel.org/r/1617715514-29039-3-git-send-email-liweihang@huawei.com


Signed-off-by: Wei Xu <xuwei5@hisilicon.com>
Signed-off-by: Shengming Shu <shushengming1@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>