vidc: Move shared memory to firmware heap

if smmu is enabled then the memory needs to be
mapped as cached for IOMMU heap, moving the
shared mmeory to firmware heap which does not
require cached mapping.

Change-Id: Ic3152e63686b51ba8768dbf38a9d9f7fdec1a963
Signed-off-by: Deepak Kotur <dkotur@codeaurora.org>