dm9000: Move the Davicom driver

Move the Davicom driver into drivers/net/ethernet/davicom/ and
make the necessary Kconfig and Makefile changes.

CC: Ben Dooks <ben@simtec.co.uk>
CC: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>