platform/x86/amd/pmf: Fix return value of amd_pmf_start_policy_engine()

platform/x86/amd/pmf: Fix return value of amd_pmf_start_policy_engine()

amd_pmf_start_policy_engine() returns an negative error code upon
failure, so the TA_PMF_* error codes cannot be used here.

Return -EIO instead. Also stop shadowing the return code in
amd_pmf_get_pb_data().

Compile-tested only.

Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Fixes: 7c45534afa44 ("platform/x86/amd/pmf: Add support for PMF Policy Binary")
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Reviewed-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Link: https://lore.kernel.org/r/20240304205005.10078-2-W_Armin@gmx.de
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>