iommu: msm: prefetch issue workaround not needed for LPAE

Following fix introduced workaround for the case where TCU
prefetch wrongly crossed 1K boundary for v7s page-table
format. For details about the prefetch hardware issue,
please refer CR 644219.

    commit 236cef42
    iommu: msm: Workaround for SMMU PTE prefetch HW bug

The commit applies fix for LPAE also, which is not needed as
LPAE second and third level tables are already 4KB aligned.

This also leads to incorrectly flushing beyond allocated
(4KB) region.

Remove this workaround for LPAE page tables since it is not
needed in the very first place.

CRs-fixed: 657961
Change-Id: I81d72067c2e858af4616ec8fcabe74cc581acdfb
Signed-off-by: Shiraz Hashim <shashim@codeaurora.org>