imx: imx6ul: Add support for Kontron Electronics SL/BL i.MX6UL/ULL boards (N63xx/N64xx)

This adds support for i.MX6UL/ULL-based evaluation kits with SoMs by
Kontron Electronics GmbH.

Currently there are the following SoM flavors (SoM-Line):
  * N6310: SOM with i.MX6UL-2, 256MB RAM, 256MB SPI NAND
  * N6311: SOM with i.MX6UL-2, 512MB RAM, 512MB SPI NAND
  * N6411: SOM with i.MX6ULL, 512MB RAM, 512MB SPI NAND

And the according evaluation boards (Board-Line):
  * N6310-S: Baseboard with SOM N6310, eMMC, display (optional), ...
  * N6311-S: Baseboard with SOM N6311, eMMC, display (optional), ...
  * N6411-S: Baseboard with SOM N6411, eMMC, display (optional), ...

Currently U-Boot describes i.MX6UL and i.MX6ULL through separate config
options at compile-time. Though the differences are so minor, that for
the scope of these SoMs we just use a single defconfig that is compatible
with both SoCs.

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Stefano Babic <sbabic@denx.de>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index 45740a4..a0b95d7 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -815,7 +815,9 @@
 	imx6ul-liteboard.dtb \
 	imx6ul-phytec-segin-ff-rdk-nand.dtb \
 	imx6ul-pico-hobbit.dtb \
-	imx6ul-pico-pi.dtb
+	imx6ul-pico-pi.dtb \
+	imx6ul-kontron-n631x-s.dtb \
+	imx6ull-kontron-n641x-s.dtb
 
 dtb-$(CONFIG_MX6ULL) += \
 	imx6ull-14x14-evk.dtb \