pointer allocation is done through `AllocateValidatedPointerPayload`.
This function was not updated to use the registered allocators in the
descriptor to perform the allocation. This patch makes use of the
allocator.
The footer word is not set and not checked for allocator other than the
default one. The support will likely come in a follow up patch but this
will necessitate more functions to be registered to be able to set and
get the footer value when the allocation in on the device.