since commit
	3e62af82 (ARM: imx: select USE_OF)
ARM_MXC already selects USE_OF, so there is no need to repeat it for
MACH_IMX31_DT
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>