ARM: shmobile: koelsch: Add I2C support

This adds I2C[1245] busses support to Koelsch board.
I2C[03] do not have any slave devices connected and
are not used because of the following:
* I2C0 pins are multiplexed with LBSC pins;
* I2C3 pins are multiplexed with EtherMAC and VIN0 pins.

Signed-off-by: Valentine Barshak <valentine.barshak@cogentembedded.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>