ARM: dts: omap3-beagle{-xm}: Add support for BeagleBoard

This commit adds OMAP3 BeagleBoard devicetree files from
Linux v4.15-rc5. This includes standard OMAP34XX board revisions as
well as the 'xM' which is OMAP36XX.

Signed-off-by: Derald D. Woods <woods.technical@gmail.com>
diff --git a/arch/arm/dts/omap3-beagle-xm-ab-u-boot.dtsi b/arch/arm/dts/omap3-beagle-xm-ab-u-boot.dtsi
new file mode 100644
index 0000000..5325f0f
--- /dev/null
+++ b/arch/arm/dts/omap3-beagle-xm-ab-u-boot.dtsi
@@ -0,0 +1,29 @@
+/*
+ * U-Boot additions
+ *
+ * (C) Copyright 2017 Derald D. Woods <woods.technical@gmail.com>
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+ */
+
+/ {
+	chosen {
+		stdout-path = &uart3;
+	};
+};
+
+&mmc1 {
+	cd-inverted;
+};
+
+&uart1 {
+	reg-shift = <2>;
+};
+
+&uart2 {
+	reg-shift = <2>;
+};
+
+&uart3 {
+	reg-shift = <2>;
+};