cpufreq: SPEAr: Add CPUFreq driver

SPEAr is an ARM based family of SoCs. This patch adds in support of cpufreq
driver for SPEAr SoCs. It is supported via DT only and so bindings are present
in binding document.

Signed-off-by: Deepak Sikri <deepak.sikri@st.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index ade7e92..159e997 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -904,6 +904,7 @@
 
 config PLAT_SPEAR
 	bool "ST SPEAr"
+	select ARCH_HAS_CPUFREQ
 	select ARCH_REQUIRE_GPIOLIB
 	select ARM_AMBA
 	select CLKDEV_LOOKUP