cpufreq/amd-pstate: Fix setting of CPPC.min_perf in active mode for performance governor

cpufreq/amd-pstate: Fix setting of CPPC.min_perf in active mode for performance governor

In the "active" mode of the amd-pstate driver with performance
governor, the CPPC.min_perf is expected to be the nominal_perf.

However after commit a9b9b4c2a4cd ("cpufreq/amd-pstate: Drop min and
max cached frequencies"), this is not the case when the governor is
switched from performance to powersave and back to performance, and
the CPPC.min_perf will be equal to the scaling_min_freq that was set
for the powersave governor.

This is because prior to commit a9b9b4c2a4cd ("cpufreq/amd-pstate:
Drop min and max cached frequencies"), amd_pstate_epp_update_limit()
would unconditionally call amd_pstate_update_min_max_limit() and the
latter function would enforce the CPPC.min_perf constraint when the
governor is performance.

However, after the aforementioned commit,
amd_pstate_update_min_max_limit() is called by
amd_pstate_epp_update_limit() only when either the
scaling_{min/max}_freq is different from the cached value of
cpudata->{min/max}_limit_freq, which wouldn't have changed on a
governor transition from powersave to performance, thus missing out on
enforcing the CPPC.min_perf constraint for the performance governor.

Fix this by invoking amd_pstate_epp_udpate_limit() not only when the
{min/max} limits have changed from the cached values, but also when
the policy itself has changed.

Fixes: a9b9b4c2a4cd ("cpufreq/amd-pstate: Drop min and max cached frequencies")
Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20250821042638.356-1-gautham.shenoy@amd.com
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>