NVME FC counters don't reflect actual results

Since counters are not atomic, or protected by a lock, the values often
get screwed up.

Make them atomic, like NVMET.  Fix up sysfs and debugfs display
accordingly Added Outstanding IOs to stats display
Signed-off-by: NDick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: NJames Smart <james.smart@broadcom.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>