board: ge: bx50v3: sync devicetrees from Linux

Copy device trees from linux, keeping them as separate files for
each board to ease future sync.

Update board code to use generic bx50v3 dt initially, then select
the specific dt based on board detection.

Signed-off-by: Robert Beckett <bob.beckett@collabora.com>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index 9d51d10..77608d2 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -851,7 +851,12 @@
 	mt8516-pumpkin.dtb \
 	mt8518-ap1-emmc.dtb
 
-dtb-$(CONFIG_TARGET_GE_BX50V3) += imx6q-bx50v3.dtb
+dtb-$(CONFIG_TARGET_GE_BX50V3) += \
+	imx6q-bx50v3.dtb \
+	imx6q-b850v3.dtb \
+	imx6q-b650v3.dtb \
+	imx6q-b450v3.dtb
+
 dtb-$(CONFIG_TARGET_MX53PPD) += imx53-ppd.dtb
 
 dtb-$(CONFIG_TARGET_VEXPRESS_CA5X2) += vexpress-v2p-ca5s.dtb