cpufreq: tegra: create CONFIG_ARM_TEGRA_CPUFREQ

currently Tegra cpufreq driver gets built based on ARCH_TEGRA, which doesn't
depend on nor select CPU_FREQ itself, so:

        select CPU_FREQ_TABLE if CPU_FREQ

... isn't guaranteed to fire.

The correct solution seems to be:

* Add CONFIG_ARM_TEGRA_CPUFREQ to drivers/cpufreq/Kconfig.arm.
* Make that Kconfig option selct CPU_FREQ_TABLE.
* Make that Kconfig option be def_bool ARCH_TEGRA.
* Modify drivers/cpufreq/Makefile to build tegra-cpufreq.c based on that.
* Remove all the cpufreq-related stuff from arch/arm/mach-tegra/Kconfig.

That way, tegra-cpufreq.c can't be built if !CPU_FREQ, and Tegra's
cpufreq works the same way as all the other cpufreq drivers.

This patch does it.

Suggested-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

arch/arm/mach-tegra/Kconfig

@@ -28,7 +28,6 @@ config ARCH_TEGRA_2x_SOC
 	select ARM_ERRATA_754327 if SMP
 	select ARM_ERRATA_764369 if SMP
 	select ARM_GIC
-	select CPU_FREQ_TABLE if CPU_FREQ
 	select CPU_V7
 	select PINCTRL
 	select PINCTRL_TEGRA20
@@ -46,7 +45,6 @@ config ARCH_TEGRA_3x_SOC
 	select ARM_ERRATA_754322
 	select ARM_ERRATA_764369 if SMP
 	select ARM_GIC
-	select CPU_FREQ_TABLE if CPU_FREQ
 	select CPU_V7
 	select PINCTRL
 	select PINCTRL_TEGRA30
@@ -63,7 +61,6 @@ config ARCH_TEGRA_114_SOC
 	select ARM_ARCH_TIMER
 	select ARM_GIC
 	select ARM_L1_CACHE_SHIFT_6
-	select CPU_FREQ_TABLE if CPU_FREQ
 	select CPU_V7
 	select PINCTRL
 	select PINCTRL_TEGRA114

drivers/cpufreq/Kconfig.arm

@@ -154,3 +154,11 @@ config ARM_SPEAR_CPUFREQ
 	default y
 	help
 	  This adds the CPUFreq driver support for SPEAr SOCs.
+
+config ARM_TEGRA_CPUFREQ
+	bool "TEGRA CPUFreq support"
+	depends on ARCH_TEGRA
+	select CPU_FREQ_TABLE
+	default y
+	help
+	  This adds the CPUFreq driver support for TEGRA SOCs.

drivers/cpufreq/Makefile

@@ -71,7 +71,7 @@ obj-$(CONFIG_ARM_S5PV210_CPUFREQ)	+= s5pv210-cpufreq.o
 obj-$(CONFIG_ARM_SA1100_CPUFREQ)	+= sa1100-cpufreq.o
 obj-$(CONFIG_ARM_SA1110_CPUFREQ)	+= sa1110-cpufreq.o
 obj-$(CONFIG_ARM_SPEAR_CPUFREQ)		+= spear-cpufreq.o
-obj-$(CONFIG_ARCH_TEGRA)		+= tegra-cpufreq.o
+obj-$(CONFIG_ARM_TEGRA_CPUFREQ)		+= tegra-cpufreq.o
 
 ##################################################################################
 # PowerPC platform drivers