isci: merge port ready substates into primary state machine

This conversion was complicated by the fact that the ready state exit routine
took unconditional action beyond just stopping the substate machine (like in
previous conversions).  In order to ensure identical behaviour every state
transition needs to be instrumented to catch ready-->!ready transitions and
execute scic_sds_port_invalidate_dummy_remote_node()

Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Piotr Sawicki <piotr.sawicki@intel.com>
[fix ready state exit handling]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>