mxc: first set GPIO level, then switch direction to output

Make sure not to create spurious pulses on GPIOs, when configuring them as
output: first set required level, then switch direction.

Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>