[SCSI] add supported_mode and active_mode attributes to the host

This adds supported_mode and active_mode attributes to
/sys/class/sys_host/hostX/ for specifying the mode that a lld supports
and the currently activated mode. The output format is similar to fc
rport roles:

luce:/sys/class/scsi_host/host0$ cat supported_mode
Initiator
luce:/sys/class/scsi_host/host0$ cat active_mode
Initiator

The mode values uses bitmap since we would support dual-mode llds in
the future like this:

luce:/sys/class/scsi_host/host0$ cat supported_mode
Initiator, Target

The supported_mode attribute looks at a scsi_host_template and the
active_mode attribute looks at a scsi_host. We would add a hook to a
scsi_host_template to change the active_mode attribute
dynamically. But now there is no hook since no lld supports that
feature.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 96bc312..adc9559 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -342,6 +342,7 @@
 	shost->unchecked_isa_dma = sht->unchecked_isa_dma;
 	shost->use_clustering = sht->use_clustering;
 	shost->ordered_tag = sht->ordered_tag;
+	shost->active_mode = sht->supported_mode;
 
 	if (sht->max_host_blocked)
 		shost->max_host_blocked = sht->max_host_blocked;