hpsa: remove incorrect BUG_ONs checking for raid offload enable

hpsa: remove incorrect BUG_ONs checking for raid offload enable

In set_encrypt_ioaccel2() and in hpsa_scsi_ioaccel_raid_map
there were BUG_ONs that looked like this:

	BUG_ON(!(dev->offload_config && dev->offload_enabled));

But, In hpsa_ack_ctlr_events() we have this,

	/* Stop sending new RAID offload reqs via the IO accelerator */
	scsi_block_requests(h->scsi_host);
	for (i = 0; i < h->ndevices; i++)
		h->dev[i]->offload_enabled = 0;
	hpsa_drain_accel_commands(h);

So, we set offload_enabled = 0 for all drives, then do this
drain_accel_commands, so that means accel commands could still
be in flight, ie. perhaps having just been submitted into
hpsa_scsi_ioaccel_raid_map concurrent with ->offload_enabled
having just been set to zero.

Reviewed-by: Scott Teel <scott.teel@pmcs.com>
Signed-off-by: Don Brace <don.brace@pmcs.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>