[SCSI] libiscsi: Added support to show targetalias in sysfs

sysfs patch to view target alias:
  /sys/class/iscsi_session/session*/targetalias

Signed-off-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>