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/board/aristainetos/common/Kconfig b/board/aristainetos/common/Kconfig
index e26de51..945a2c4 100644
--- a/board/aristainetos/common/Kconfig
+++ b/board/aristainetos/common/Kconfig
@@ -2,10 +2,7 @@
 	int "select version of aristainetos board"
 	help
 	  version of aristainetos board version
-	  2 version 2
-	  3 version 2b
-	  4 version 2bcsl
-	  5 version 2c
+	  5 version 2c and 2d
 
 config SYS_I2C_MXC_I2C1
 	default y