ARM: imx_v6_v7_defconfig: enable CONFIG_CPU_FREQ_STAT

It is very useful for user to retrieve cpufreq transtion statistics
and worth to be default enabled.
Signed-off-by: NDong Aisheng <aisheng.dong@nxp.com>
Reviewed-by: NFabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm/configs/imx_v6_v7_defconfig

@@ -55,6 +55,7 @@ CONFIG_FORCE_MAX_ZONEORDER=14
 CONFIG_CMDLINE="noinitrd console=ttymxc0,115200"
 CONFIG_KEXEC=y
 CONFIG_CPU_FREQ=y
+CONFIG_CPU_FREQ_STAT=y
 CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y
 CONFIG_CPU_FREQ_GOV_POWERSAVE=y
 CONFIG_CPU_FREQ_GOV_USERSPACE=y