ARM: dts: Add new "generic" am4372 device tree file.

With U-boot runtime board detect for DTB selection a "default" dtb needs
to be created. This will be used temporarily until the "proper" dtb is
selected.

Also, add -u-boot.dtsi for AM437x SK and IDK to enable I2C for
board detection via DM_I2C.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
diff --git a/arch/arm/dts/am437x-sk-evm-u-boot.dtsi b/arch/arm/dts/am437x-sk-evm-u-boot.dtsi
new file mode 100644
index 0000000..2f68d7a
--- /dev/null
+++ b/arch/arm/dts/am437x-sk-evm-u-boot.dtsi
@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+/{
+	ocp {
+		u-boot,dm-spl;
+	};
+};
+
+&uart0 {
+	u-boot,dm-spl;
+};
+
+&i2c0 {
+	u-boot,dm-spl;
+};
+
+&mmc1 {
+	u-boot,dm-spl;
+};