mx31moboard: clean-up of board support

Various improvements (includes in alphabetical order, platform devices
declaration order change, ...)

The pins now are claimed in a single function call from a main table for
every board for a better clarity and to adopt the current agreement for
mx31 devices.

Signed-off-by: Valentin Longchamp <valentin.longchamp@epfl.ch>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>