atl*: Move the Atheros drivers

Move the Atheros drivers into drivers/net/ethernet/atheros/ and
make the necessary Kconfig and Makefile changes.

CC: Jay Cliburn <jcliburn@gmail.com>
CC: Chris Snook <chris.snook@gmail.com>
CC: Jie Yang <jie.yang@atheros.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>