scsi: scsi_dh_alua: Correct comment for alua_alloc_pg()

In the comment for function alua_alloc_pg() the argument '@h' is
mistakenly referred to.  Fix this by replacing it with the correct
argument reference, '@tpgs', and provide a short description.
Signed-off-by: John Pittman <jpittman@redhat.com>
Reviewed-by Laurence Oberman <loberman@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/device_handler/scsi_dh_alua.c

@@ -214,8 +214,8 @@ static struct alua_port_group *alua_find_get_pg(char *id_str, size_t id_size,
 /*
  * alua_alloc_pg - Allocate a new port_group structure
  * @sdev: scsi device
- * @h: alua device_handler data
  * @group_id: port group id
+ * @tpgs: target port group settings
  *
  * Allocate a new port_group structure for a given
  * device.