ARC: [plat-hsdk] use actual clk driver to manage cpu clk

With corresponding clk driver now merged upstream, switch to it.

 - core_clk now represent the PLL (vs. fixed clk before)
 - input_clk represent the clk signal src for PLL (basically xtal)
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/boot/dts/hsdk.dts

@@ -57,10 +57,10 @@ cpu@3 {
 		};
 	};
 
-	core_clk: core-clk {
+	input_clk: input-clk {
 		#clock-cells = <0>;
 		compatible = "fixed-clock";
-		clock-frequency = <500000000>;
+		clock-frequency = <33333333>;
 	};
 
 	cpu_intc: cpu-interrupt-controller {
@@ -102,6 +102,13 @@ soc {
 
 		ranges = <0x00000000 0xf0000000 0x10000000>;
 
+		core_clk: core-clk@0 {
+			compatible = "snps,hsdk-core-pll-clock";
+			reg = <0x00 0x10>, <0x14B8 0x4>;
+			#clock-cells = <0>;
+			clocks = <&input_clk>;
+		};
+
 		serial: serial@5000 {
 			compatible = "snps,dw-apb-uart";
 			reg = <0x5000 0x100>;

arch/arc/plat-hsdk/Kconfig

@@ -7,3 +7,4 @@
 
 menuconfig ARC_SOC_HSDK
 	bool "ARC HS Development Kit SOC"
+	select CLK_HSDK