vfio: vfio_pci_nvlink2: use a vma helper function

Use a vma helper function to simply code.
Signed-off-by: Peng Hao <richard.peng@oppo.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/pci/vfio_pci_nvlink2.c

@@ -161,8 +161,7 @@ static int vfio_pci_nvgpu_mmap(struct vfio_pci_device *vdev,
 
 	atomic_inc(&data->mm->mm_count);
 	ret = (int) mm_iommu_newdev(data->mm, data->useraddr,
-			(vma->vm_end - vma->vm_start) >> PAGE_SHIFT,
-			data->gpu_hpa, &data->mem);
+			vma_pages(vma), data->gpu_hpa, &data->mem);
 
 	trace_vfio_pci_nvgpu_mmap(vdev->pdev, data->gpu_hpa, data->useraddr,
 			vma->vm_end - vma->vm_start, ret);