netdev: Added KS8842 driver

This is a driver for the Micrel KS8842 ethernet switch.

The supplied code is for driving the KS8842 through the Timberdale FPGA
on the Russellville board, a development board for Intel Atom CPU
in the automotive area.

Signed-off-by: Richard Röjfors <richard.rojfors.ext@mocean-labs.com>
Signed-off-by: David S. Miller <davem@davemloft.net>