isci: remove base_controller abstraction

Merge struct sci_base_controller into scic_sds_controller, and also factor
the two types of state machine handlers into one function.  While we're at
it also remove lots of duplicate incorrect kerneldoc comments for the state
machine handlers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>