rockchip: dts: rk3399-puma: refactor and rename (default) DDR3-1600 DTS

To better support different RAM timings (DDR3-1333 and DDR3-1866 are
assembly options for the RK3399-Q7), this refactors the DTS support
and renames the default DTS variant from rk3399-puma to
rk3399-puma-ddr1600:
- changes the rk3399-puma DTS into a board-specific DTSI by removing
  the inclusion of the DRAM timings
- adds a new rk3399-puma-ddr1600.dts, which includes the (new) common
  board DTSI and the DDR3-1600 timing DTSI
- wires this up from arch/arm/dts/Makefile and configs/puma-rk3399_defconfig

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/dts/rk3399-puma-ddr1600.dts b/arch/arm/dts/rk3399-puma-ddr1600.dts
new file mode 100644
index 0000000..31aaf70
--- /dev/null
+++ b/arch/arm/dts/rk3399-puma-ddr1600.dts
@@ -0,0 +1,11 @@
+/*
+ * (C) Copyright 2017 Theobroma Systems Design und Consulting GmbH
+ *
+ * SPDX-License-Identifier:     GPL-2.0+	X11
+ */
+
+/dts-v1/;
+
+#include "rk3399-puma.dtsi"
+#include "rk3399-sdram-ddr3-1600.dtsi"
+