qcom-cpufreq: Use CONFIG_CPU_FREQ_MSM to compile qcom-cpufreq

The config string used for compiling qcom-cpufreq was changed from
CONFIG_CPU_FREQ_MSM to CONFIG_ARCH_MSM in
d0e09738 (msm: cpufreq: Move cpufreq
to drivers/cpufreq/)

However, not all targets with CONFIG_ARCH_MSM will always have cpufreq
enabled all the time. Previous change leads to definition errors when
CONFIG_CPU_FREQ_MSM is not selected on certain MSM targets.

Change-Id: I1f99e27282032ab62216100e5712b751dcc10fe9
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>