i2c: octeon: Add support for cn78xx chips

cn78xx has a different interrupt architecture, so we have to manage
the interrupts differently.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Jan Glauber <jglauber@cavium.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

bindings: i2c: use consistent naming for i2c binding descriptions

Filenames of devictree binding documentation seems to be arbitrary and
for me it is unneeded hazzle to find the corresponding documentation for
a specific driver.

Naming the description the same as the driver is a lot easier and makes
sense to me since the driver defines the binding it understands.

Also, remove a reference in one source to the binding documentation, since path
information easily gets stale.

Signed-off-by: Wolfram Sang <wolfram@the-dreams.de>
Cc: Rob Herring <robherring2@gmail.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>