korina: Move the IDT driver

Move the IDT driver into drivers/net/ethernet/ and make the
necessary Kconfig and Makefile changes

CC: "IDT Inc." <rischelp@idt.com>
CC: Felix Fietkau <nbd@openwrt.org>
CC: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>