imx: properly protect mach/mx{1,[25][157x]}.h from multiple inclusion

Some headers have used (now) wrong names or havn't had protection at
all.  This is needed before adding static inline functions to the
headers.

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: Magnus Lilja <lilja.magnus@gmail.com>
Cc: Holger Schurig <hs4233@mail.mn-solutions.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Daniel Mack <daniel@caiaq.de>