PCI: hv: Take a const cpumask in hv_compose_msi_req_get_cpu()

The cpumask that is passed to this function ultimately comes from
irq_data_get_effective_affinity_mask(), which was recently changed to
return a const cpumask pointer. The first level of functions handling
the affinity mask were updated, but not this helper function.

Fixes: 4d0b8298 ("genirq: Return a const cpumask from irq_data_get_affinity_mask")
Reported-by: Nkernel test robot <lkp@intel.com>
Signed-off-by: NSamuel Holland <samuel@sholland.org>
Reviewed-by: NMichael Kelley <mikelley@microsoft.com>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220708004931.1672-1-samuel@sholland.org

drivers/pci/controller/pci-hyperv.c

@@ -1635,7 +1635,7 @@ static u32 hv_compose_msi_req_v1(
  * Create MSI w/ dummy vCPU set targeting just one vCPU, overwritten
  * by subsequent retarget in hv_irq_unmask().
  */
-static int hv_compose_msi_req_get_cpu(struct cpumask *affinity)
+static int hv_compose_msi_req_get_cpu(const struct cpumask *affinity)
 {
 	return cpumask_first_and(affinity, cpu_online_mask);
 }