pcm037: add MT9T031 camera support

Add support for the MT9T031 CMOS camera sensor from Aptina to the PCM037
board. Also add two I2C iomux pin definitions, needed for pcm037. Also
remove now unneeded #ifdef CONFIG_I2C_IMX.

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