i40e: set num_queue_pairs to num configured by VF

Change vsi->num_queue_pairs to equal the number that are configured
by the VF. This, in turn, limits the number of queues that are
enable/disabled. This fixes the mismatched case for when a VF configures
fewer queues than is allocated to it by the PF.

Change other sections to use alloc_queue_pairs as warranted.

Change-ID: I0de1b55c9084e7be6acc818da8569f12128a82c2
Signed-off-by: Ashish Shah <ashish.n.shah@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>