ARM: dts: msm: Have adsp heap use secure memory CMA pool for 8992

To support new computer vision usecases, the adsp heap will
share the CMA pool with the secure memory.

CRs-fixed: 783377
Change-Id: I1b13bfea9d2cc704890f39126b5158e68a5befa5
Signed-off-by: Liam Mark <lmark@codeaurora.org>