msm: cpufreq: Fix msm_cpufreq_get_freq() for sync CPUs

When CPUs are in sync, only CPU0 has a non-NULL cpu_clk.
clk_get_rate()
on other cpu_clk will return 0. msm_cpufreq_get_freq() is
used in multiple
places in cpufreq framework to determine current
hardware frequency.

Fix msm_cpufreq_get_freq() to return the right
hardware frequency for
systems with synchronous CPUs.

Change-Id:
I6a880764ad51fa9a257a328798b38d574750686a
Signed-off-by: Junjie Wu
<junjiew@codeaurora.org>

idea is taken here -
https://github.com/poondog/android_kernel_google_msm/commit/a7e944881c74f2c7a266924b6aa309166e391ef6