cpufreq: stats: Remove redundant cpufreq_cpu_get() call

__cpufreq_stats_create_table always gets pass the valid and real policy
struct. So, there's no need to call cpufreq_cpu_get() to get the policy
again.

Change-Id: I0136b3e67018ee3af2335906407f55d8c6219f71
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>