msm: vidc: Allow non-contiguous allocations for secure buffers

Pass a flag to ion to allow non-contiguous allocations with an sg list
of 1MB chunks for secure buffers.

Change-Id: I49a101cf7c20be0fa80aafb8476d0192436b7d90
Signed-off-by: Shalaj Jain <shalajj@codeaurora.org>