iommu: arm-smmu: Enable io-coherency in bypass mode

Support io-coherency on a per context bank basis when
in bypass mode. The SCTLR register provides the ability
to override the shareability and cacheability attributes
when translations are disabled for a particular context
bank i.e in bypass mode. Hence if the client/dev associated
with the context bank is io-coherent, then set the
appropriate SCTLR register attributes to enable io-coherency
If the client/dev is not io-coherent, then force bypass
transactions for them to be non-shareable.

Change-Id: I621bc369fb4206f3a7edf342ea50fcf5a2f869e9
Signed-off-by: Swathi Sridhar <swatsrid@codeaurora.org>