nvme: Add ctrl attributes for queue_count and sqsize

Current controller interrogation requires a lot of guesswork
on how many io queues were created and what the io sq size is.
The numbers are dependent upon core/fabric defaults, connect
arguments, and target responses.

Add sysfs attributes for queue_count and sqsize.

Signed-off-by: James Smart <jsmart2021@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>