cpufreq/amd-pstate-ut: Adjust variable scope

In amd_pstate_ut_check_freq() and amd_pstate_ut_check_perf() the cpudata
variable is only needed in the scope of the for loop. Move it there.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Reviewed-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>