qla2xxx: Fix regression introduced by target configFS changes

this patch fixes following regression

 # targetcli
 [Errno 13] Permission denied: '/sys/kernel/config/target/qla2xxx/21:00:00:0e:1e:08:c7:20/tpgt_1/enable'

Fixes: 2eafd72939fd ("target: use per-attribute show and store methods")
Signed-off-by: Himanshu Madhani <himanshu.madhani@qlogic.com>
Signed-off-by: Giridhar Malavali <giridhar.malavali@qlogic.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/scsi/qla2xxx/tcm_qla2xxx.c

@@ -902,7 +902,7 @@ static ssize_t tcm_qla2xxx_tpg_fabric_prot_type_show(struct config_item *item,
 	return sprintf(page, "%d\n", tpg->tpg_attrib.fabric_prot_type);
 }
 
-CONFIGFS_ATTR_WO(tcm_qla2xxx_tpg_, enable);
+CONFIGFS_ATTR(tcm_qla2xxx_tpg_, enable);
 CONFIGFS_ATTR_RO(tcm_qla2xxx_tpg_, dynamic_sessions);
 CONFIGFS_ATTR(tcm_qla2xxx_tpg_, fabric_prot_type);