siemens: capricorn: move to cxg3 reference project with deneb board

We have many HW with capricorn i.MX8X boards. The difference in u-boot is
at all by the display of the LEDs.

* put upstream a reference project & board for DT and defconfig
* use the capricorn prefix outside the board/siemens/capricorn folder

Signed-off-by: Enrico Leto <enrico.leto@siemens.com>
Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index 042282f..d81a9f9 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -935,8 +935,7 @@
 	fsl-imx8qxp-ai_ml.dtb \
 	fsl-imx8qxp-colibri.dtb \
 	fsl-imx8qxp-mek.dtb \
-	imx8-deneb.dtb \
-	imx8-giedi.dtb
+	imx8-capricorn-cxg3.dtb \
 
 dtb-$(CONFIG_ARCH_IMX8ULP) += \
 	imx8ulp-evk.dtb