xen/arm: smmuv3: Remove the page 1 fixup

xen/arm: smmuv3: Remove the page 1 fixup

Backport Linux commit 86d2d9214880. This is the clean backport without
any changes.

Since we now keep track of page 1 via a separate pointer that
already encapsulates aliasing to page 0 as necessary, we can remove
the clunky fixup routine and simply use the relevant bases directly.
The current architecture spec (IHI0070D.a) defines
SMMU_{EVENTQ,PRIQ}_{PROD,CONS} as offsets relative to page 1, so the
cleanup represents a little bit of convergence as well as just
lines of code saved.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Origin: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 86d2d9214880
Signed-off-by: Rahul Singh <rahul.singh@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>