RDMA/hns: Convert cq_table to XArray

Change the locking to not disable interrupts as the lookup in interrupt
context will not see a freed CQ, thanks to the synchronize_irq() call
before freeing the CQ.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>