platform/x86/amd/hsmp: improve the error log

platform/x86/amd/hsmp: improve the error log

1. Change print message during platform init to a more meaningful
   clear message.
2. Return the error code returned by hsmp_test() itself, rather then
   returning a common EOPNOTSUPP error.

Signed-off-by: Suma Hegde <suma.hegde@amd.com>
Reviewed-by: Naveen Krishna Chatradhi <nchatrad@amd.com>
Link: https://lore.kernel.org/r/20231010120310.3464066-3-suma.hegde@amd.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>