mips/octeon: 16-Bit NOR flash was not being detected during boot

The cavium code assumed that all NOR on the boot bus was
an 8-bit NOR part and hardcoded the bankwidth. The simple
solution was to add the code that queries the configuration
register for the width of the bus that has been hardware strapped
to the Cavium. This allows both 8-bit and 16-bit parts to be
discovered during boot.

Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: Charles Hardin <ckhardin@exablox.com>
Patchwork: http://patchwork.linux-mips.org/patch/4323


Signed-off-by: John Crispin <blogic@openwrt.org>