ks8*/ksz8*: Move the Micrel drivers

Move the Micrel drivers into drivers/net/ethernet/micrel/ and
make the necessary Kconfig and Makefile changes.

CC: Ben Dooks <ben@simtec.co.uk>
CC: Tristram Ha <Tristram.Ha@micrel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>