cpufreq/amd-pstate: Move all EPP tracing into *_update_perf and *_set_epp functions

The EPP tracing is done by the caller today, but this precludes the
information about whether the CPPC request has changed.

Move it into the update_perf and set_epp functions and include information
about whether the request has changed from the last one.
amd_pstate_update_perf() and amd_pstate_set_epp() now require the policy
as an argument instead of the cpudata.

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