iommu/dma: Plumb in the per-CPU IOVA caches

With IOVA allocation suitably tidied up, we are finally free to opt in
to the per-CPU caching mechanism. The caching alone can provide a modest
improvement over walking the rbtree for weedier systems (iperf3 shows
~10% more ethernet throughput on an ARM Juno r1 constrained to a single
650MHz Cortex-A53), but the real gain will be in sidestepping the rbtree
lock contention which larger ARM-based systems with lots of parallel I/O
are starting to feel the pain of.

Reviewed-by: Nate Watterson <nwatters@codeaurora.org>
Tested-by: Nate Watterson <nwatters@codeaurora.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Git-commit: bb65a64c7285e7105c1a6c8a33b37770343a4e96
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


[pdaly@codeaurora.org: Resolve conflicts due to missing msi changes]

Change-Id: I8b0ef39e577e22b914fc10cfdcf5482b41bd6661
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>