iommu: msm: make iommu map and unmap atomic

Certain use cases require iommu map and unmap functions
to be called from atomic context. Remove all sleeping
calls and fix the locks to make these functions atomic.
The secure map and unmap functions are still non-atomic
since they have to invoke smc calls which are sleeping
functions right now.

Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Change-Id: I802b1aed98d30bf75b381fadcb5fc68978618a3f