isci: unify constants

cross driver constants are spread out over multiple header files, consolidate
them into isci.h, and push some includes out to the source files that need
them.

TODO: remove SCI_MODE_SIZE infrastructure.
TODO: task.h is full of inlines that are too large

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/scsi/isci/request.c b/drivers/scsi/isci/request.c
index 4961ee3..a580728 100644
--- a/drivers/scsi/isci/request.c
+++ b/drivers/scsi/isci/request.c
@@ -62,6 +62,7 @@
 #include "sata.h"
 #include "scu_completion_codes.h"
 #include "scic_sds_request.h"
+#include "scic_controller.h"
 #include "sas.h"
 
 static enum sci_status isci_request_ssp_request_construct(