arm64: defconfig: Enable e1000 device

Enables e1000 Ethernet device as it is used as a low-cost failover
Ethernet port on various QorIQ reference boards.  Enabled as built-in
for booting from network without initramfs.

Signed-off-by: Li Yang <leoyang.li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>