staging: ion: uapi: match the existing heap type enums

Change the enup order for ion heap types to match how it was before so
as to not break any userspace code that depends on them.

Bug: 140507100
Test: ion-unit-tests

Change-Id: Id68c50a9bd3eda2ce46bc88a326a120c52d1110f
Signed-off-by: Sandeep Patil <sspatil@google.com>