imx6: remove not longer supported aristainetos boards

Removed aristainetos2, 2b, 2b-csl. This boards have been
recalled and destroyed.

Adapt board code to remove stuff not needed anymore.

Fix checkpatch warning, remove fdt_high and initrd_high
from default environment.

Signed-off-by: Heiko Schocher <hs@denx.de>
zu remove
diff --git a/arch/arm/dts/imx6dl-aristainetos2c_7.dts b/arch/arm/dts/imx6dl-aristainetos2c_7.dts
index 35435e1..00eec82 100644
--- a/arch/arm/dts/imx6dl-aristainetos2c_7.dts
+++ b/arch/arm/dts/imx6dl-aristainetos2c_7.dts
@@ -11,6 +11,6 @@
 #include "imx6qdl-aristainetos2c.dtsi"
 
 / {
-	model = "aristainetos2c i.MX6 Dual Lite Board 7";
+	model = "aristainetos2c+2d i.MX6 Dual Lite Boards 7";
 	compatible = "fsl,imx6dl";
 };