qcom-cpufreq: Allow all CPUs to get cpu_clk on targets with sync CPUs

For targets with synchronous CPU clocks, only CPU0 has a clock pointer in
cpu_clks[]. This forces CPU0 to be the last CPU to be hotplugged out, or go
to certain low power mode that needs to disable CPU clocks.

Remove this requirement by adding clock pointer for all CPUs. Drivers
that ask for CPU clocks will get same clock for CPUs in sync.

Change-Id: Ib97af2c3b0fdbc8dbb78364178225cc64ed02036
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>