cpufreq/amd-pstate: Use boost numerator for upper bound of frequencies

commit 18d9b522 ("cpufreq/amd-pstate: Use nominal perf for limits
when boost is disabled") introduced different semantics for min/max limits
based upon whether the user turned off boost from sysfs.

This however is not necessary when the highest perf value is the boost
numerator.

Suggested-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@amd.com>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Fixes: 18d9b522 ("cpufreq/amd-pstate: Use nominal perf for limits when boost is disabled")
Link: https://lore.kernel.org/r/20241209185248.16301-3-mario.limonciello@amd.com


Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>