The board files in mach-imx are the only users of iomux drivers and
headers.  Move them into mach-imx from plat-mxc.
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>
Acked-by: NSascha Hauer <s.hauer@pengutronix.de>
Acked-by: NArnd Bergmann <arnd@arndb.de>