[SCSI] add srp transport class

This adds srp transport class that works with ib_srp and ibmvscsi.

It creates only /sys/class/{srp_host,srp_remote_ports} and
srp_remote_ports has only "port_id" attribute.

viola:/sys/class/srp_remote_ports/port-0:1# ls
device  port_id  subsystem  uevent
viola:/sys/class/srp_remote_ports/port-0:1# cat port_id
4c:49:4e:55:58:20:56:49:4f:00:00:00:00:00:00:00

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig
index d2b3898..50d3062 100644
--- a/drivers/scsi/Kconfig
+++ b/drivers/scsi/Kconfig
@@ -289,6 +289,13 @@
 
 source "drivers/scsi/libsas/Kconfig"
 
+config SCSI_SRP_ATTRS
+	tristate "SRP Transport Attributes"
+	depends on SCSI
+	help
+	  If you wish to export transport-specific information about
+	  each attached SRP device to sysfs, say Y.
+
 endmenu
 
 menuconfig SCSI_LOWLEVEL