Kunpeng930 supports queue doorbell isolation.
When doorbell isolation is enabled, it supports to obtain the
maximum number of queues of one function from hardware register.
Otherwise, the 'max_qp_num' is the total number of queues.

When assigning queues to VF, it is necessary to ensure that the number
of VF queues does not exceed 'max_qp_num'.
Signed-off-by: Weili Qian <qianweili@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>