msm_11ad: Set atomic attribute to SMMU driver

Set DOMAIN_ATTR_ATOMIC attribute to SMMU driver so that
it can handle DMA map/unmap operations from atomic context
which is required by 11ad driver

Change-Id: I7e538e6c41e5f40ff01dcfc9cbecf860ded22057
Signed-off-by: Hamad Kadmany <hkadmany@codeaurora.org>