iommu/arm-smmu: Use existing facilities for I/O Coherent PTWs

The SMMU driver currently uses the IO_PGTABLE_QUIRK_NO_DMA
quirk to convey to the IO pagetable code that the IOMMU's
pagetable walker is IO coherent with the CPUs. Instead,
remove the usage of IO_PGTABLE_QUIRK_NO_DMA in the SMMU
driver in lieu of the existing coherent_walk variable
in the pagetable configuration structure, which conveys
the same information.

Change-Id: I14308a20d5f85efe4b3f62c71bcbd2a18d0b08a1
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>