imx: only define deprecated symbols conditionally

Define deprecated symbols in an #ifdef IMX_NEEDS_DEPRECATED_SYMBOLS ...

All files that still depend on the old definitions get
-DIMX_NEEDS_DEPRECATED_SYMBOLS passed to the compiler.

When all remaining users are fixed this allows including the soc
specific headers unconditionally.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Eric Benard <eric@eukrea.com>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Alan Carvalho de Assis <acassis@gmail.com>
Cc: Daniel Mack <daniel@caiaq.de>
Cc: Alberto Panizzo <maramaopercheseimorto@gmail.com>
Cc: Ilya Yanok <yanok@emcraft.com>
Cc: Holger Schurig <hs4233@mail.mn-solutions.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Magnus Lilja <lilja.magnus@gmail.com>