iommu/arm-smmu: Rationalize TLB sync timeout handling

The current TLB sync timeout handling doesn't make sense
in the context of non QSMMU-V500 SMMU V2 implementations, so
introduce the notion of architecture specific handling
for TLB sync timeouts.

Change-Id: Ibceb5422d6488f9e67cc4c4ed968348ad92aa834
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>