8139*/atp/r8169/sc92031: Move the Realtek drivers

Move the Realtek drivers into drivers/net/ethernet/realtek/ and make
the necessary Kconfig and Makefile changes.

CC: Realtek linux nic maintainers <nic_swsd@realtek.com>
CC: Francois Romieu <romieu@fr.zoreil.com>
CC: Jeff Garzik <jgarzik@pobox.com>
CC: Donald Becker <becker@scyld.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>