iommu/arm-smmu: fix table flushing during initial allocations

Now that we populate page tables as we traverse them ("iommu/arm-smmu:
fix pud/pmd entry fill sequence"), we need to ensure that we flush out
our zeroed tables after initial allocation, to prevent speculative TLB
fills using bogus data.

This patch adds additional calls to arm_smmu_flush_pgtable during
initial table allocation, and moves the dsb required by coherent table
walkers into the helper.

Change-Id: I5aa087126f75495766c68c5ee4252fcd683fe461
Cc: <stable@vger.kernel.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Git-commit: 6dd35f45b8dac827b6f9dd86f5aca6436cdd2410
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>