cpufreq for freescale mx51

Currently, only two operating points: 160Mhz and 800Mhz.
the operating points are tested on babbage 3.0

Signed-off-by: Yong Shen <yong.shen@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 553b7cf..12115ff 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1584,6 +1584,12 @@
 
 source "drivers/cpufreq/Kconfig"
 
+config CPU_FREQ_IMX
+	tristate "CPUfreq driver for i.MX CPUs"
+	depends on ARCH_MXC && CPU_FREQ
+	help
+	  This enables the CPUfreq driver for i.MX CPUs.
+
 config CPU_FREQ_SA1100
 	bool