thunderbolt: Return -ENOTCONN when ERR_CONN is received

This allows the calling code to distinguish if the error was due to
ERR_CONN (adapter is disconneced or disabled) or something else. Will be
needed in USB4 router NVM update in the following patch.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/ctl.c

@@ -962,6 +962,9 @@ static int tb_cfg_get_error(struct tb_ctl *ctl, enum tb_cfg_space space,
 
 	if (res->tb_error == TB_CFG_ERROR_LOCK)
 		return -EACCES;
+	else if (res->tb_error == TB_CFG_ERROR_PORT_NOT_CONNECTED)
+		return -ENOTCONN;
+
 	return -EIO;
 }