ARM: dts: vf610-zii-cfu1: Run I2C0 at 400 kHz

All the I2C devices connected to the I2C0 bus are capable of
running at 400kHz, so run it at a higher frequency.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Tested-by: Chris Healy <cphealy@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>