habanalabs: block WREG_BULK packet on PDMA

WREG_BULK is a special packet that has a variable length. Therefore, we
can't parse it when validating CBs that go to the PCI DMA queue. In case
the user needs to use it, it can put multiple WREG32 packets instead.

Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
Reviewed-by: Omer Shpigelman <oshpigelman@habana.ai>