vfio/iommu_type1: replace kfree with kvfree

Variables allocated by kvzalloc should not be freed by kfree.
Because they may be allocated by vmalloc.
So we replace kfree with kvfree here.

Fixes: d6a4c185

 ("vfio iommu: Implementation of ioctl for dirty pages tracking")
Signed-off-by: Jiacheng Shi <billsjc@sjtu.edu.cn>
Link: https://lore.kernel.org/r/20211212091600.2560-1-billsjc@sjtu.edu.cn


Signed-off-by: Alex Williamson <alex.williamson@redhat.com>