omap: ion: Fix heap id for new ion handle in omap_tiler_alloc

ION allocations from the non-secure tiler heap could not be freed.
The ION heaps used from alloc and free were different causing a
mismatch at the genpool level and triggering a kernel BUG().

Change-Id: I76c43fd9d375b66d570d205c2c8ce00335b54cbb
Signed-off-by: Tony Lofthouse <a0741364@ti.com>