qcom-cpufreq: Use cpufreq_table_validate_and_show to fill freq_table

cpufreq_table_validate_and_show() is created as a standard way to
initialize frequency for a policy and assign freq_table. Use this new
API to assign freq_table.

CRs-Fixed: 1024229
Change-Id: Iac3a9394790e140492c5c0c0ad6d068840bfffa4
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>
Signed-off-by: Harsh Shandilya <msfjarvis@gmail.com>