ARM: dts: at91: Add dts files for at91sam9260ek/9g20ek

The device tree source files of at91sam9g20ek and at91sam9260ek
boards are copied from the Linux v4.10, do the changes below.
 - Fix the build error for the usb0 node.
 - Add the reg property for the pinctrl node.
 - Move the gpio (pioA, pioB, pioC ...) nodes as the pinctrl's
   slibling nodes, instead of the child nodes.
 - Add the "u-boot,dm-pre-reloc" property for the dbgu node are used
   in board_init_f stage.
 - Add the clk pinctrl of the mmc0 node.
 - Fix the compilation warnings.

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/dts/at91sam9g20.dtsi b/arch/arm/dts/at91sam9g20.dtsi
index f593016..e88d73c 100644
--- a/arch/arm/dts/at91sam9g20.dtsi
+++ b/arch/arm/dts/at91sam9g20.dtsi
@@ -40,7 +40,7 @@
 			};
 
 			pmc: pmc@fffffc00 {
-				plla: pllack {
+				plla: pllack@0 {
 					atmel,clk-input-range = <2000000 32000000>;
 					atmel,pll-clk-output-ranges = <745000000 800000000 0 0>,
 								<695000000 750000000 1 0>,
@@ -52,7 +52,7 @@
 								<400000000 450000000 3 1>;
 				};
 
-				pllb: pllbck {
+				pllb: pllbck@1 {
 					compatible = "atmel,at91sam9g20-clk-pllb";
 					atmel,clk-input-range = <2000000 32000000>;
 					atmel,pll-clk-output-ranges = <30000000 100000000 0 0>;