iw_cxgb4: remove BUG_ON() usage.

iw_cxgb4 has many BUG_ON()s that were left over from various enhancemnets
made over the years.  Almost all of them should just be removed.  Some,
however indicate a ULP usage error and can be handled w/o bringing down
the system.

If the condition cannot happen with correctly implemented cxgb4 sw/fw,
then remove the BUG_ON.

If the condition indicates a misbehaving ULP (like CQ overflows), add
proper recovery logic.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/cxgb4/id_table.c

@@ -73,7 +73,6 @@ void c4iw_id_free(struct c4iw_id_table *alloc, u32 obj)
 	unsigned long flags;
 
 	obj -= alloc->start;
-	BUG_ON((int)obj < 0);
 
 	spin_lock_irqsave(&alloc->lock, flags);
 	clear_bit(obj, alloc->table);