board: Move SF heap below FW heap

On certain memory configurations the MFC heap
might get allocated 256MB away from the FW heap
because the SF heap is allocated between FW and
MFC heap. Video hardware requires the gap between FW
and MFC heap to be less than 256MB.

Move the SF heap down below the firmware heap in
the list of heaps in the platform data to make sure
MFC heap is allocated closer to FW heap.

CRs-fixed: 337244
Change-Id: I21e29fcb413d63955686c750451884024a469e3f
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>