ion: msm: Add support for querying the security state of heaps

ION clients may want to know about the security state of a heap
prior to allocating from it, so expose an interface for querying
the security state of a heap.

Change-Id: Ibf832792ffbc81b5b96b8ddbc507db5418a47928
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>