ARC: Add model property to boards .dts

1. This way we sync with Linux kernel where we have model
   set for all ARC boards for quite some time, see [1]

2. Once we enable DISPLAY_BOARDINFO for ARC this info will
   be printed on boot givin some extra data-point about the board

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=618a9cd06dd471ac232f5b27325b24d26eba5571

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

arch/arc/dts/abilis_tb100.dts

@@ -7,6 +7,8 @@
 #include "skeleton.dtsi"
 
 / {
+	model = "abilis,tb100";
+
 	aliases {
 		console = &uart0;
 	};

arch/arc/dts/axs101.dts

@@ -9,6 +9,8 @@
 
 
 / {
+	model = "snps,axs101";
+
 	chosen {
 		stdout-path = &uart0;
 	};

arch/arc/dts/axs103.dts

@@ -9,6 +9,8 @@
 
 
 / {
+	model = "snps,axs103";
+
 	chosen {
 		stdout-path = &uart0;
 	};

arch/arc/dts/emdk.dts

@@ -7,6 +7,8 @@
 #include "skeleton.dtsi"
 
 / {
+	model = "snps,emdk";
+
 	#address-cells = <1>;
 	#size-cells = <1>;
 

arch/arc/dts/hsdk.dts

@@ -8,6 +8,8 @@
 #include "dt-bindings/clock/snps,hsdk-cgu.h"
 
 / {
+	model = "snps,hsdk";
+
 	#address-cells = <1>;
 	#size-cells = <1>;
 

arch/arc/dts/nsim.dts

@@ -7,6 +7,8 @@
 #include "skeleton.dtsi"
 
 / {
+	model = "snps,nsim";
+
 	aliases {
 		console = &arcuart0;
 	};