ARM: mxs: look up timrot clock from device tree

Change call clk_get_sys() to of_clk_get() to look up timrot clock from
device tree, so that the clk_register_clkdev() call for timrot can be
saved in clock driver.
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx23.dtsi

@@ -426,6 +426,7 @@
 				compatible = "fsl,imx23-timrot", "fsl,timrot";
 				reg = <0x80068000 0x2000>;
 				interrupts = <28 29 30 31>;
+				clocks = <&clks 28>;
 			};
 
 			auart0: serial@8006c000 {

arch/arm/boot/dts/imx28.dtsi

@@ -838,6 +838,7 @@
 				compatible = "fsl,imx28-timrot", "fsl,timrot";
 				reg = <0x80068000 0x2000>;
 				interrupts = <48 49 50 51>;
+				clocks = <&clks 26>;
 			};
 
 			auart0: serial@8006a000 {

arch/arm/mach-mxs/timer.c

@@ -247,7 +247,7 @@ static void __init mxs_timer_init(struct device_node *np)
 	struct clk *timer_clk;
 	int irq;
 
-	timer_clk = clk_get_sys("timrot", NULL);
+	timer_clk = of_clk_get(np, 0);
 	if (IS_ERR(timer_clk)) {
 		pr_err("%s: failed to get clk\n", __func__);
 		return;

drivers/clk/mxs/clk-imx23.c

@@ -159,8 +159,6 @@ int __init mx23_clocks_init(void)
 		of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data);
 	}
 
-	clk_register_clkdev(clks[clk32k], NULL, "timrot");
-
 	for (i = 0; i < ARRAY_SIZE(clks_init_on); i++)
 		clk_prepare_enable(clks[clks_init_on[i]]);
 

drivers/clk/mxs/clk-imx28.c

@@ -237,7 +237,6 @@ int __init mx28_clocks_init(void)
 		of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data);
 	}
 
-	clk_register_clkdev(clks[xbus], NULL, "timrot");
 	clk_register_clkdev(clks[enet_out], NULL, "enet_out");
 
 	for (i = 0; i < ARRAY_SIZE(clks_init_on); i++)