Use new blk-mq interfaces. Use multiple queues and also use the block
layer complete helper that finish the IO on the CPU that initiated it.
Reviewed-by: NJan Hoeppner <hoeppner@linux.vnet.ibm.com>
Signed-off-by: NStefan Haberland <sth@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>