msm: iommu: Synchronize access to IOMMU cfg port

Add remote spinlock that allows CPU and GPU to
synchronize access to IOMMU hardware.

Add usage of remote spinlock to iommu driver and
add depenency on SFPB hardware mutex being enabled.`

This feature is not using SFPB hardware mutex. However,
SFPB hardware mutex must be enabled since the remote
spinlock implementation is making use of shared memory
that is normally used when SFPB hardware mutex is not enabled.

Change-Id: Idc622f3484062e0721493be3cbbfb8889ed9d800
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>