[POWERPC] MPC8568E-MDS: add support for ds1374 rtc

MPC8568E-MDS have DS1374 chip on the I2C bus, thus let's use it.
This patch also adds #address-cells and #size-cells to the I2C
controllers nodes.

p.s. DS1374 rtc class driver is in the -mm tree, its name is
rtc-rtc-class-driver-for-the-ds1374.patch.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>