platform/x86: ISST: Fix return value on last invalid resource

platform/x86: ISST: Fix return value on last invalid resource

When only the last resource is invalid, tpmi_sst_dev_add() is returing
error even if there are other valid resources before. This function
should return error when there are no valid resources.

Here tpmi_sst_dev_add() is returning "ret" variable. But this "ret"
variable contains the failure status of last call to sst_main(), which
failed for the invalid resource. But there may be other valid resources
before the last entry.

To address this, do not update "ret" variable for sst_main() return
status.

If there are no valid resources, it is already checked for by !inst
below the loop and -ENODEV is returned.

Fixes: 9d1d36268f3d ("platform/x86: ISST: Support partitioned systems")
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: stable@vger.kernel.org # 6.10+
Link: https://lore.kernel.org/r/20240816163626.415762-1-srinivas.pandruvada@linux.intel.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>