s390/pci: use lock-free I/O translation updates

I/O translation tables on s390 use 8 byte page table entries and tables
which are allocated lazily but only freed when the entire I/O
translation table is torn down. Also each IOVA can at any time only
translate to one physical address Furthermore I/O table accesses by the
IOMMU hardware are cache coherent. With a bit of care we can thus use
atomic updates to manipulate the translation table without having to use
a global lock at all. This is done analogous to the existing I/O
translation table handling code used on Intel and AMD x86 systems.

Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Link: https://lore.kernel.org/r/20221109142903.4080275-6-schnelle@linux.ibm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

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