cpufreq: SPEAr: Instantiate as platform_driver

As multiplatform build is being adopted by more and more
ARM platforms, initcall function should be used very carefully.
For example, when SPEAr cpufreq driver is enabled on a kernel
booted on a non-SPEAr board, we will get following boot time error:

	spear_cpufreq: Invalid cpufreq_tbl

To eliminate this undesired the effect, the patch changes SPEAr
driver to have it instantiated as a platform_driver. Then it will
only run on platforms that create the platform_device "spear-cpufreq".

This patch also creates platform node for SPEAr13xx boards.

Reported-by: Josh Cartwright <joshc@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

arch/arm/mach-spear/spear1310.c

@@ -28,6 +28,7 @@
 static void __init spear1310_dt_init(void)
 {
 	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
+	platform_device_register_simple("spear-cpufreq", -1, NULL, 0);
 }
 
 static const char * const spear1310_dt_board_compat[] = {

arch/arm/mach-spear/spear1340.c

@@ -143,6 +143,7 @@ static void __init spear1340_dt_init(void)
 {
 	of_platform_populate(NULL, of_default_bus_match_table,
 			spear1340_auxdata_lookup, NULL);
+	platform_device_register_simple("spear-cpufreq", -1, NULL, 0);
 }
 
 static const char * const spear1340_dt_board_compat[] = {

drivers/cpufreq/spear-cpufreq.c

@@ -19,6 +19,7 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
+#include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 
@@ -166,7 +167,7 @@ static struct cpufreq_driver spear_cpufreq_driver = {
 	.attr		= cpufreq_generic_attr,
 };
 
-static int spear_cpufreq_driver_init(void)
+static int spear_cpufreq_probe(struct platform_device *pdev)
 {
 	struct device_node *np;
 	const struct property *prop;
@@ -234,7 +235,15 @@ static int spear_cpufreq_driver_init(void)
 	of_node_put(np);
 	return ret;
 }
-late_initcall(spear_cpufreq_driver_init);
+
+static struct platform_driver spear_cpufreq_platdrv = {
+	.driver = {
+		.name	= "spear-cpufreq",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= spear_cpufreq_probe,
+};
+module_platform_driver(spear_cpufreq_platdrv);
 
 MODULE_AUTHOR("Deepak Sikri <deepak.sikri@st.com>");
 MODULE_DESCRIPTION("SPEAr CPUFreq driver");