imx/mach-mx2: use constants namespaced by the corresponding SOC (easy part)

This just leaves devices.c, generic.c and serial.c to clean up.  As
these files are used on more than one SOC they need some more work.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Holger Schurig <hs4233@mail.mn-solutions.de>
Cc: Rabin Vincent <rabin@rab.in>
Cc: Javier Martin <javier.martin@vista-silicon.com>
Cc: Valentin Longchamp <valentin.longchamp@epfl.ch>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Eric Benard <eric@eukrea.com>
Cc: Ivo Clarysse <ivo.clarysse@gmail.com>
Cc: Vladimir Barinov <vbarinov@embeddedalley.com>
Cc: Daniel Schaeffer <daniel.schaeffer@timesys.com>
Cc: Simon POLETTE <spolette@adnlysd018.(none)>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Alan Carvalho de Assis <acassis@gmail.com>
Cc: Luotao Fu <l.fu@pengutronix.de>