platform/x86/amd/pmc: Isolate STB code changes to a new file

platform/x86/amd/pmc: Isolate STB code changes to a new file

Since S2D (Spill to DRAM) uses different message port offsets compared to
PMC message offsets for communication with PMFW, relocate the S2D macros
from pmc.c to a new file, mp1_stb.c, for better code organization.

Following this change, it is logical to introduce a new structure,
"struct stb_arg," to pass the message, argument, and response offset
details to PMFW via the amd_pmc_send_cmd() call. Additionally, move the
s2d_msg_id member from amd_pmc_dev into the new structure.

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/20241108070822.3912689-6-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>