Use MAP_FIXED in remapNewHeap

The heap address must not change when it is remapped

Change-Id: Ia44f178932e2afe8de3d4739e7085caae8568885
Signed-off-by: Pete Delaney <piet.delaney@imgtec.com>
Signed-off-by: Chris Dearman <chris.dearman@imgtec.com>