mx31: add support for the bugbase 1.3 from buglabs

Note that the hardware schematics and documentations can be obtained
  here: http://www.bugcommunity.com/wiki/index.php/BUGbase



Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@no-log.org>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>