[POWERPC] fsl: Add CS4270 i2c data to fsl_soc.c

The i2c_devices[] array in fsl_soc.c lists all the I2C nodes that are supported
on Freescale boards.  Add an entry for the Cirrus Logic CS4270 so that a
new-style CS4270 driver will work.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>