iommu/pamu: Replace use of kzfree with kfree_sensitive

kzfree() is effectively deprecated as of commit 453431a5

 ("mm,
treewide: rename kzfree() to kfree_sensitive()") and is now simply an
alias for kfree_sensitive(). So just replace it with kfree_sensitive().

Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
Link: https://lore.kernel.org/r/20200911135325.66156-1-alex.dewar90@gmail.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>