isci: implement I_T_nexus_reset

This is a requirement for 2.6.39's new libata eh.

Still some questions about lldd_dev_gone racing against dev->lldd_dev
lookups, but we are at least no more broken than mvsas in this regard.

We also short-circuit I_T_nexus_reset invocations from the device
discovery path (IDEV_EH similar to MVS_DEV_EH) to filter out the
resulting domain rediscoveries triggered by the reset.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/scsi/isci/remote_device.h

@@ -134,6 +134,7 @@ struct isci_remote_device {
 	#define IDEV_START_PENDING 0
 	#define IDEV_STOP_PENDING 1
 	#define IDEV_ALLOCATED 2
+	#define IDEV_EH 3
 	unsigned long flags;
 	struct isci_port *isci_port;
 	struct domain_device *domain_dev;