msm: VPU: Fix handling of secure video buffers

VPU hardware can process content protetcted video in secure buffers.
Fixed control to enable secure content, and using correct ION heap.

Change-Id: I3bf3d06c533ed6a4f4b73c569f6c530b103e7a43
Signed-off-by: Ahmed Abdul-Salam <aabdulsa@codeaurora.org>