Update aristainetos board to Kconfig

aristainetos board was merged in u-boot-imx before
Kconfig was integrated, but it is not yet
mainline.

Signed-off-by: Stefano Babic <sbabic@denx.de>
CC: Heiko Schocher <hs@denx.de>
Acked-by: Heiko Schocher <hs@denx.de>
diff --git a/configs/aristainetos_defconfig b/configs/aristainetos_defconfig
new file mode 100644
index 0000000..6541865
--- /dev/null
+++ b/configs/aristainetos_defconfig
@@ -0,0 +1,3 @@
+CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/aristainetos/aristainetos.cfg,MX6DL"
+CONFIG_ARM=y
+CONFIG_TARGET_ARISTAINETOS=y