ARM: mxs: fix naming of struct holding info for mxs-i2c devices

For consistency mxs has to be repeated, one for the name space and
another one for the device name.

LAKML-Reference: 1300308028-8922-1-git-send-email-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>