bfin_mac: Move the Analog Devices Inc driver

Move the Analog Devices Inc driver into drivers/net/ethernet/adi/ and
make the necessary Kconfig and Makefile changes.

CC: <uclinux-dist-devel@blackfin.uclinux.org>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Bob Liu <bob.liu@analog.com>