gpu: ion: Stop trying to allocate from an order on first failure

With this patch the system heap will only try to allocate from each
order as long as allocations succeed.  If it failes to obtain a higher
order allocation, it doesn't retry that order.

Change-Id: I0d9144b4c30cc0e427acdcad2f1f12ae7f37f827
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>