net: libwx: fix alloc msix vectors failed

driver needs queue msix vectors and one misc irq vector,
but only queue vectors need irq affinity.
when num_online_cpus is less than chip max msix vectors,
driver will acquire (num_online_cpus + 1) vecotrs, and
call pci_alloc_irq_vectors_affinity functions with affinity
params without setting pre_vectors or post_vectors, it will
cause return error code -ENOSPC.
Misc irq vector is vector 0, driver need to set affinity params
.pre_vectors = 1.

Fixes: 3f703186

 ("net: libwx: Add irq flow functions")
Signed-off-by: Duanqiang Wen <duanqiangwen@net-swift.com>
Signed-off-by: David S. Miller <davem@davemloft.net>