MIPS: Cavium-Octeon: Add more chip specific feature tests.

The octeon-ethernet driver needs to check for additional chip specific
features, we add them to the octeon_has_feature() framework.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>