cpufreq: cpufreq-cpu0: assign cpu_dev correctly to cpu0 device

Commit f837a9b5 "cpufreq: cpufreq-cpu0:
remove device tree parsing for cpu nodes" assumed the pdev->dev is set to
cpu0 device in the platform code. But it actually points to the virtual
cpufreq-cpu0 platform device which is not present in the device tree.
Most of the information needed by cpufreq is stored in cpu0 DT node.
So cpu_dev must point to cpu0 device.

This patch fixes the wrong assignment to cpu_dev.
Reported-and-tested-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: NSudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq-cpu0.c

@@ -12,6 +12,7 @@
 #define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
 
 #include <linux/clk.h>
+#include <linux/cpu.h>
 #include <linux/cpufreq.h>
 #include <linux/err.h>
 #include <linux/module.h>
@@ -177,7 +178,11 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
 	struct device_node *np;
 	int ret;
 
-	cpu_dev = &pdev->dev;
+	cpu_dev = get_cpu_device(0);
+	if (!cpu_dev) {
+		pr_err("failed to get cpu0 device\n");
+		return -ENODEV;
+	}
 
 	np = of_node_get(cpu_dev->of_node);
 	if (!np) {