Once the IO buff allocations were made shared, there was a single XRI
buffer list shared by all hardware queues.  A single list isn't great for
performance when shared across the per-cpu hardware queues.

Create a separate XRI IO buffer get/put list for each Hardware Queue.  As
SGLs and associated IO buffers get allocated/posted to the firmware; round
robin their assignment across all available hardware Queues so that there
is an equitable assignment.

Modify SCSI and NVME IO submit code paths to use the Hardware Queue logic
for XRI allocation.

Add a debugfs interface to display hardware queue statistics

Added new empty_io_bufs counter to track if a cpu runs out of XRIs.

Replace common_ variables/names with io_ to make meanings clearer.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>