[CPUFREQ] EXYNOS: Initialize locking_frequency with initial frequency

As per definition, locking_frequency is the initial frequency which is
set by boot-loader. Hence the value is updated with the initial value
during boot time init call.

This code was present in exynos210-cpufreq.c before this consolidation
patch.
- a125a17f ([CPUFREQ] EXYNOS: Make EXYNOS common cpufreq driver).

Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Inderpal Singh <inderpal.singh@linaro.org>
Signed-off-by: Dave Jones <davej@redhat.com>