platform/x86/amd/pmc: Update function names to align with new STB file

platform/x86/amd/pmc: Update function names to align with new STB file

With STB now in a separate file, update the function names to match the
correct naming schema by removing the _pmc_ prefix where needed.

Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Co-developed-by: Sanket Goswami <Sanket.Goswami@amd.com>
Signed-off-by: Sanket Goswami <Sanket.Goswami@amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Link: https://lore.kernel.org/r/20241108070822.3912689-4-Shyam-sundar.S-k@amd.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>