[SCSI] lpfc 8.1.11 : Fix lpfc_multi_ring_support

It was not accounted for in the fast/slow rings.
Genericize the implementation and control it via sysfs

Signed-off-by: James Smart <James.Smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>