unicore32: Remove ARCH_HAS_CPUFREQ config option

This config exists entirely to hide the cpufreq menu from the
kernel configuration unless a platform has selected it. Nothing
is actually built if this config is 'Y' and it just leads to more
patches that add a select under a platform Kconfig so that some
other CPUfreq option can be chosen. Let's remove the option so
that we can always enable CPUfreq drivers on unicore32 platforms.

Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Xuetao Guan <gxt@mprc.pku.edu.cn>