MIPS: cavium-octeon: export symbols needed by octeon-ethernet

Export symbols needed by the octeon-ethernet driver. The patch fixes a
build failure with CONFIG_OCTEON_ETHERNET=m.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6166/