ipa: set IOMMU domain attributes before attaching

IOMMU domain attributes should be set *before* attaching to an IOMMU,
but we're currently setting them after attaching in the IPA driver,
which causes the attributes to be ignored.  Fix this by moving the
domain attribute setting code above the attach.

Change-Id: I94f80aed632eb4d731f94678b51d780bfddde171
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>