cpufreq/amd-pstate: Align offline flow of shared memory and MSR based systems

Set min_perf to lowest_perf for shared memory systems, similar to the MSR
based systems.

Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Link: https://lore.kernel.org/r/20241023102108.5980-5-Dhananjay.Ugwekar@amd.com


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