i2c: i2c-ocores: DT bindings and minor fixes.

Cleanups to i2c-cores, no change in logic, changes are:
* Move i2c-ocores device tree documentation from source file to
  Documentation/devicetree/bindings/i2c/i2c-ocores.txt.
* Add \n to dev_warn and dev_err messages where missing
* Minor updates to the text and formatting fixes.

Signed-off-by: Jayachandran C <jayachandranc@netlogicmicro.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>