ARCv2: [dts]: Introduce HS38 specific include DTS ...

... and add them to plat-sim DTS.

This allows for future change to introduce timers in DT in single place

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/boot/dts/nsimosci_hs.dts b/arch/arc/boot/dts/nsimosci_hs.dts
index 034a313..983f691 100644
--- a/arch/arc/boot/dts/nsimosci_hs.dts
+++ b/arch/arc/boot/dts/nsimosci_hs.dts
@@ -7,7 +7,7 @@
  */
 /dts-v1/;
 
-/include/ "skeleton.dtsi"
+/include/ "skeleton_hs.dtsi"
 
 / {
 	compatible = "snps,nsimosci_hs";