net: aquantia: fixed buffer overflow

The overflow is detected by smatch:

drivers/net/ethernet/aquantia/atlantic/aq_pci_func.c: 175
  aq_pci_func_free_irqs() error: buffer overflow 'self->aq_vec' 8 <= 31

In reality msix_entry_mask always restricts number of iterations.
Adding extra condition to make logic clear and smatch happy.
Signed-off-by: Nikita Danilov <nikita.danilov@aquantia.com>
Signed-off-by: Igor Russkikh <igor.russkikh@aquantia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/aquantia/atlantic/aq_pci_func.c

@@ -170,6 +170,8 @@ void aq_pci_func_free_irqs(struct aq_nic_s *self)
 	for (i = 32U; i--;) {
 		if (!((1U << i) & self->msix_entry_mask))
 			continue;
+		if (i >= AQ_CFG_VECS_MAX)
+			continue;
 
 		if (pdev->msix_enabled)
 			irq_set_affinity_hint(pci_irq_vector(pdev, i), NULL);